Obtaining titanium dioxide nanoparticles with spherical shape and antimicrobial properties using M. citrifolia leaves extract by hydrothermal method.

PubMed

M, Sundrarajan; K, Bama; M, Bhavani; S, Jegatheeswaran; S, Ambika; A, Sangili; P, Nithya; R, Sumathi

2017-06-01

In this work, we synthesized titanium dioxide (TiO 2 ) nanoparticles using leaf extract of Morinda citrifolia (M. citrifolia) by the advanced hydrothermal method. The synthesized TiO 2 nanoparticles were characterized by X-ray diffraction (XRD), Fourier transmission infrared (FT-IR), Ultraviolet-visible diffuse reflectance (UV-Vis DRS), Ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM with EDX) techniques. The XRD major peak at 27.3° corresponds to the (110) lattice plane of tetragonal rutile TiO 2 phase and average crystalline size of nanoparticles is 10nm. The FT-IR result confirmed that TiO 2 nanoparticles and the presences of very few amount of anthraquinone and phenolic compounds of the leaf extract. The obtained nanoparticles were also characterized by UV-Vis DRS absorption spectroscopy and an intense band at 423nm clearly reveals the formation of nanoparticles. SEM images with EDX spectra clearly reveal the size of the nanoparticles, between 15 and 19nm in excellent quasi-spherical shape, by virtue of stabilization (capping) agent. The presence of elements-titanium and oxygen was verified with EDX spectrum. Furthermore, the inhibitory activity of green synthesized TiO 2 nanoparticles was tested against human pathogens like Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger by the agar well-diffusion method. The TiO 2 nanoparticles exhibited superior antimicrobial activity against Gram-positive bacteria, demonstrating their antimicrobial value against pathogenic diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

Green chemistry approach for the synthesis of ZnO-carbon dots nanocomposites with good photocatalytic properties under visible light.

PubMed

Bozetine, Hakima; Wang, Qi; Barras, Alexandre; Li, Musen; Hadjersi, Toufik; Szunerits, Sabine; Boukherroub, Rabah

2016-03-01

We report on a simple and one-pot synthetic method to produce ZnO/carbon quantum dots (ZnO/CQDs) nanocomposites. The morphological features and chemical composition of the nanocomposites were characterized using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analyses (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical properties of the nanocomposites were examined using UV-visible (UV-vis) spectrophotometry. The photocatalytic activity of the ZnO/CQDs was evaluated for the degradation of a model organic pollutant, rhodamine B, under visible light irradiation at room temperature. The highly efficient photodegradation capability of the nanocomposite was demonstrated by comparison with ZnO particles, prepared using identical experimental conditions. Overall, the present approach adheres to green chemistry principles and the nanocomposite holds promise for the development of remarkably efficient catalytic systems. Copyright © 2015 Elsevier Inc. All rights reserved.

Investigation of tin oxide nanofibers synthesized via bio-template technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kundu, Virender Singh, E-mail: vskundu-kuk@rediffmail.com; Dhiman, Jonny; Kumar, Suresh

In the present paper tin oxide nanofibers have been by synthesized using cotton as bio-template via sol-gel route. This is comparatively a new synthesis technique. The structure and morphology of the obtained SnO{sub 2} nanofibers were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX). The optical properties of the same have been studied by using UV-Vis spectroscopy. The observed XRD pattern showed that peaks are very narrow and sharp which indicates crystalline nature of samples. SEM images gave an idea about the sample morphology and confirm that the obtained sample were nanofibers. The optical absorbancemore » spectrum of the sample under study was recorded in UV-visible region (200nm- 800nm). The band gap of the sample was found to be 3.95 eV which is higher than their bulk counterpart.« less

AgBr/MgBi2O6 heterostructured composites with highly efficient visible-light-driven photocatalytic activity

NASA Astrophysics Data System (ADS)

Zhong, Liansheng; Hu, Chaohao; Zhuang, Jing; Zhong, Yan; Wang, Dianhui; Zhou, Huaiying

2018-06-01

AgBr/MgBi2O6 heterostructured photocatalysts were synthesized by the deposition-precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS) were employed to examine the phase structure, morphology and optical properties of the as-prepared samples. The photocatalytic activity was investigated by decomposing methylene blue (MB) solution under visible light irradiation (λ > 420 nm). AgBr/MgBi2O6 composites exhibited significantly enhanced visible-light-driven photocatalytic properties in comparison with pure MgBi2O6 and AgBr. When the molar ratio of AgBr to MgBi2O6 was 3:1, the composite catalyst showed the optimal photocatalytic activity and excellent stability. The enhanced photocatalytic activity of AgBr/MgBi2O6 composites was attributed to the formation of p-n heterojunction between AgBr and MgBi2O6, thereby resulting in the effective separation and transfer of photogenerated electrons-hole pairs.

Synthesis of N-doped potassium tantalate perovskite material for environmental applications

NASA Astrophysics Data System (ADS)

Rao, Martha Purnachander; Nandhini, Vellangattupalayam Ponnusamy; Wu, Jerry J.; Syed, Asad; Ameen, Fuad; Anandan, Sambandam

2018-02-01

Nitrogen containing potassium tantalate perovskite material has been synthesized by the solvothermal method using urea (CH4N2O) as a nitrogen source. The as-prepared sample was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance spectroscopy (DRS), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The particle size of nitrogen containing KTaO3 observed from SEM images was found to be 100-150 nm. Doping KTaO3 with nitrogen causes reduction of band gap from 3.5 to 2.54 eV. The incorporation of Nitrogen into the crystal lattice of KTaO3 not only extended the absorption of light from UV (ultraviolet) region to visible region and also enhanced the photocatalytic activity. As prepared nitrogen containing KTaO3 samples exhibit cubic-like morphology and noticed efficient photocatalytic activity towards methylene blue dye degradation under visible light illumination. The intermediates formed during photodegradation were identified by mass spectrometry (GC-MS) and proposed suitable degradation pathway.

Increased photocatalytic activity of TiO 2 mesoporous microspheres from codoping with transition metals and nitrogen

DOE PAGES

Mathis, John E.; Lieffers, Justin J.; Mitra, Chandrima; ...

2015-11-06

The composition of anatase TiO 2 was modified by codoping using combinations of a transition metal and nitrogen in order to increase its photocatalytic activity and extend it performance in the visible region of the electromagnetic spectrum. The transition metals (Mn, Co, Ni, Cu) were added during the hydrothermal preparation of mesoporous TiO 2 particles, and the nitrogen was introduced by post-annealing in flowing ammonia gas at high temperature. The samples were analyzed by SEM, XRD, BET, inductively-coupled plasma spectroscopy, and diffuse reflectance UV-vis spectroscopy. The photocatalytic activity was assessed by observing the change in methylene blue concentrations under bothmore » UV-vis and visible-only light irradiation. As a result, the photocatalytic activity of the (Mn,N), (Co,N), (Cu,N), and Ni,N) codoped TiO 2 was significantly enhanced relative to (N) TiO 2.« less

Facile fabrication of Ag3VO4/attapulgite composites for highly efficient visible light-driven photodegradation towards organic dyes and tetracycline hydrochloride

NASA Astrophysics Data System (ADS)

Luo, Yuting; Luo, Jie; Duan, Guorong; Liu, Xiaoheng

2017-12-01

An efficient one-dimensional attapulgite (ATP)-based photocatalyst, Ag3VO4/ATP nanocomposite, was fabricated by a facile deposition precipitation method with well-dispersed Ag3VO4 nanoparticles anchored on the surface of natural ATP fibers. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and UV-visible diffused reflectance spectroscopy (UV-vis DRS) were employed to investigate the morphologies, structure, and optical property of the prepared photocatalysts. The photocatalytic experiments indicated that the Ag3VO4/ATP nanocomposites exhibited enhanced visible light-driven photocatalytic activity towards the degradation of rhodamine B (RhB), methyl orange (MO), and tetracycline hydrochloride (TCH), of which the 20 wt% Ag3VO4/ATP sample showed superb photocatalytic performance. As demonstrated by N2 adsorption-desorption, photocurrent measurements, electrochemical impedance spectroscopy (EIS), and photoluminescence (PL) spectra analyses, the improved photocatalytic activity arose from the enlarged surface area, the facilitated charge transfer, and the suppressed recombination of photogenerated charge carriers in Ag3VO4/ATP system. Furthermore, radical scavengers trapping experiments and recycling tests were also conducted. This work gives a new insight into fabrication of highly efficient, stable, and cost-effective visible light-driven photocatalyst for practical application in wastewater treatment and environmental remediation.

Enhanced visible-light photocatalysis and gas sensor properties of polythiophene supported tin doped titanium nanocomposite

NASA Astrophysics Data System (ADS)

Chandra, M. Ravi; Siva Prasada Reddy, P.; Rao, T. Siva; Pammi, S. V. N.; Siva Kumar, K.; Vijay Babu, K.; Kiran Kumar, Ch.; Hemalatha, K. P. J.

2017-06-01

The polythiophene supported tin doped titanium nanocomposites (PTh/Sn-TiO2) were synthesized by modified sol-gel process through oxidative polymerization of thiophene. The fourier transform infrared spectroscopy (FT-IR) and UV-Vis diffuse reflectance spectroscopy (UV-DRS) analysis confirms the existence of synergetic interaction between metal oxide and polymer along with extension of absorption edge to visible region. The composites are found to be in spherical form with core-shell structure, which is confirmed by scanning electron spectroscopy (SEM) and transmission electron microscopy (TEM) images, the presence of all respective elements of composite are proven by energy-dispersive X-ray spectroscopy (EDX) analysis. The importance of polythiophene on surface of metal oxide has been were studied as a function of photocatalytic activity for degradation of organic pollutant congo red and gas sensor behavior towards liquid petroleum gas (LPG). All the composites are photocatalytically active and the composite with 1.5 wt% thiophene degrades the pollutant congo red within 120 min when compared to remaining catalysts under visible light irradiation. On the other hand, same composite have shown potential gas sensor properties towards LPG at 300 °C. Considering all the results, it can be noted that polythiophene acts as good sensitizer towards LPG and supporter for the tin doped titania that improve the photocatalytic activity under visible light.

Green Synthesis of Silver Nanoparticles Using an Aqueous Extract of Monotheca buxifolia (Flac.) Dcne

NASA Astrophysics Data System (ADS)

Anwar, Natasha; Khan, Abbas; Shah, Mohib; Anwar, Saad

2018-01-01

This study deals with the synthesis and physicochemical investigation of silver nanoparticles using an aqueous extract of Monotheca buxifolia (Flac.). On the treatment of aqueous solution of silver nitrate with the plant extract, silver nanoparticles were rapidly fabricated. The synthesized particles were characterized by using UV-visible spectrophotometry (UV), Fourier transform infrared spectroscopy (FTIR), Energy dispersive X-ray (EDX) and Scanning electron microscopy (SEM). The formation of AgNPs was confirmed by noting the change in colour through visual observations as well as via UV-Vis spectroscopy. UV-Vis spectrum of the aqueous medium containing silver nanoparticles showed an absorption peak at around 440 nm. FTIR was used to identify the chemical composition of silver nanoparticles and Ag-capped plant extract. The presence of elemental silver was also confirmed through EDX analysis. The SEM analysis of the silver nanoparticles showed that they have a uniform spherical shape with an average size in the range of 40-78 nm. This green system showed better capping and stabilizing agent for the fine particles. Further, in vitro the antioxidant activity of Monotheca buxifolia (Flac.) and Ag-capped with the plant was also evaluated using FeCl3/K3Fe (CN)6 essay.

Structural, optical and photoelectric properties of sprayed CdS thin films

NASA Astrophysics Data System (ADS)

Chandel, Tarun; Dwivedi, Shailendra Kumar; Zaman, M. Burhanuz; Rajaram, P.

2018-05-01

In this study, CdS thin films were grown via a facile spray pyrolysis technique. The crystalline phase, morphological, compositional and optical properties of the CdS thin films have been studied using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and UV-vis absorption spectroscopy, respectively. XRD patterns show that the grown CdS films crystallized in the hexagonal structure. Scanning electron microscopy (SEM) study shows that the surfaces of the films are smooth and are uniformly covered with nanoparticles. EDAX results reveal that the grown films have good stochiometry. UV-vis spectroscopy shows that the grown films have transparency above 80% over the entire visible region. The photo-electric response of the CdS films grown on glass substrates has been observed.

Structural and optical properties of colloidal InZnO NPs prepared by laser ablation in liquid

NASA Astrophysics Data System (ADS)

khlewee, Maryam M.; Khashan, Khawla S.

2018-05-01

In the current work, colloidal of InZnO NPs were produced by pulsed laser ablation in liquid (PLAL) method. The effect of indium content on the structural, morphological and optical of the InZnO NPs was confirmed by Fourier transform infrared spectroscopy, Scanning electron microscopy, and UV-visible spectroscopy. The FTIR spectra showed the presence of the metal-oxide bond. The SEM exhibit different morphological aspects according to the (In/Zn) ratio. The optical transmittance of InZnO NPs has high value around 70 % in the visible region and the band gap value was varied between 3.29 to 3.25 eV.

UV and visible activation of Cr(III)-doped TiO2 catalyst prepared by a microwave-assisted sol-gel method during MCPA degradation.

PubMed

Mendiola-Alvarez, S Y; Guzmán-Mar, J L; Turnes-Palomino, G; Maya-Alejandro, F; Hernández-Ramírez, A; Hinojosa-Reyes, L

2017-05-01

Photocatalytic degradation of 4-chloro-2-methylphenoxyacetic acid (MCPA) in aqueous solution using Cr(III)-doped TiO 2 under UV and visible light was investigated. The semiconductor material was synthesized by a microwave-assisted sol-gel method with Cr(III) doping contents of 0.02, 0.04, and 0.06 wt%. The catalyst was characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), nitrogen physisorption, UV-Vis diffuse reflectance spectroscopy (DRS), and atomic absorption spectroscopy (AAS). The photocatalytic activity for the photodegradation of MCPA was followed by reversed-phase high-performance liquid chromatography (HPLC) and total organic carbon (TOC) analysis. The intermediates formed during degradation were identified using gas chromatography-mass spectrometry (GC-MS). Chloride ion evolution was measured by ion chromatography. Characterization results showed that Cr(III)-doped TiO 2 materials possessed a small crystalline size, high surface area, and mesoporous structure. UV-Vis DRS showed enhanced absorption in the visible region as a function of the Cr(III) concentration. The Cr(III)-doped TiO 2 catalyst with 0.04 wt% of Cr(III) was more active than bare TiO 2 for the degradation of MCPA under both UV and visible light. The intermediates identified during MCPA degradation were 4-chloro-2-methylphenol (CMP), 2-(4-hydroxy-2-methylphenoxy) acetic acid (HMPA), and 2-hydroxybuta-1,3-diene-1,4-diyl-bis (oxy)dimethanol (HBDM); the formation of these intermediates depended on the radiation source.

Silver nanoparticle production by Rhizopus stolonifer and its antibacterial activity against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banu, Afreen; Rathod, Vandana, E-mail: drvandanarathod@rediffmail.com; Ranganath, E.

Highlights: {yields} Silver nanoparticle production by using Rhizopus stolonifer. {yields} Antibacterial activity of silver nanoparticles against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae. {yields} Synergistic effect of antibiotics with silver nanoparticles towards ESBL-strains. {yields} Characterization of silver nanoparticles made by UV-vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, atomic force microscopy (AFM). -- Abstract: This report focuses on the synthesis of silver nanoparticles using the fungus, Rhizopus stolonifer and its antimicrobial activity. Research in nanotechnology highlights the possibility of green chemistry pathways to produce technologically important nanomaterials. Characterization of newly synthesized silvermore » nanoparticles was made by UV-visible absorption spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy and atomic force microscope (AFM). TEM micrograph revealed the formation of spherical nanoparticles with size ranging between 3 and 20 nm. The biosynthesized silver nanoparticles (AgNPs) showed excellent antibacterial activity against ESBL-strains which includes E. coli, Proteus. sp. and Klebsiella sp.« less

Synthesis, characterization and antimicrobial activity of dextran sulphate stabilized silver nanoparticles

NASA Astrophysics Data System (ADS)

Cakić, Milorad; Glišić, Slobodan; Nikolić, Goran; Nikolić, Goran M.; Cakić, Katarina; Cvetinov, Miroslav

2016-04-01

Dextran sulphate stabilized silver nanoparticles (AgNPs - DS) were synthesized from aqueous solution of silver nitrate (AgNO3) and dextran sulphate sodium salt (DS). The characterization of AgNPs - DS was performed by ultraviolet-visible spectroscopy (UV-VIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and antimicrobial activity. The formation of AgNPs - DS was monitored by colour changes of the reaction mixture from yellowish to brown and by measuring the surface plasmon resonance absorption peak in UV-VIS spectra at 420 nm. The SEM analysis was used for size and shape determination of AgNPs - DS. The presence of elemental silver and its crystalline structure in AgNPs - DS were confirmed by EDX and XRD analyses. The possible functional groups of DS responsible for the reduction and stabilization of AgNPs were determinated by FTIR spectroscopy. The AgNPs - DS showed strong antibacterial activity against Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 11778, Bacillus luteus in haus strain, Bacillus subtilis ATTC 6633, Listeria monocytogenes ATCC 15313, Escherichia coli ATTC 25922, Pseudomonas aeruginosa ATTC 27853, Klebsiella pneumoniae ATTC 700603, Proteus vulgaris ATTC 8427, and antifungal activity against Candida albicans ATTC 2091.

Synthesis and Characterization of Cobalt Substituted Zinc Ferrite Nanoparticles by Microwave Combustion Method.

PubMed

Sundararajan, M; Kennedy, L John; Vijaya, J Judith

2015-09-01

Pure and cobalt doped zinc ferrites were prepared by microwave combustion method using L-arginine as a fuel. The prepared samples were characterized by various instrumental techniques such as X-ray powder diffractometry, high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis, Fourier transformed infrared (FT-IR) spectroscopy, photoluminescence spectroscopy and UV-Visible diffuse reflectance spectroscopy. Vibrating sample magnetometry at room temperature was recorded to study the magnetic behavior of the samples. X-ray analysis confirmed the formation of zinc ferrites normal spinel-type structure with an average crystallite sizes in the range, 25.69 nm to 35.68 nm. The lattice parameters decreased as cobalt fraction was increased. The HR-SEM images showed nanoparticles are agglomerated. The estimated band gap energy value was found to decrease with an increase in cobalt content (1.87 to 1.62 eV). Broad visible emissions are observed in the photoluminescence spectra. A gradual increase in the coercivity and saturation magnetization (M(s)) were noted at relatively higher cobalt doping fractions.

Hybrid Magnetic Core-Shell Nanophotocatalysts for Environmental Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaulden, Patrick; Murph, Simona Hunyadi

2016-07-29

This research study describes a facile sol-gel method to creating hybrid iron (III) oxide/silica/titania nanomaterials decorated with gold nanoparticles for use in environmental applications. The multi-functional composition of the nanomaterials allows for photocatalyzed reactions to occur in both the visible and the UV range. The morphologies, elemental composition, and surface charge of the nanoparticles were determined by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Phase Analysis Light Scattering (PALS), respectively. The photocatalytic activity of the synthesized hybrid nanoparticles for breaking down a model analyte, methyl orange (MO), was then evaluated using UV-Vis Spectroscopy. The efficiency of themore » photocatalyst under UV light irradiation was measured and compared to other well-studied nanophotocatalysts, namely titanium oxide and iron oxide nanoparticles. The concentration dependence of both the photocatalyst and the analyte was also investigated. By utilizing the known UV-active properties of TiO 2, the magnetic properties of Fe 2O 3, the optical properties of gold in the visible range of the spectrum, and the high stability of silica, a novel, highly efficient photocatalyst that is active on a broad range of the spectrum (UV-Vis) can be created to destroy organic pollutants in wastewater streams.« less

Rapid green synthesis of silver nanoparticles by aqueous extract of seeds of Nyctanthes arbor-tristis

NASA Astrophysics Data System (ADS)

Basu, Shibani; Maji, Priyankar; Ganguly, Jhuma

2016-01-01

The present study explores that the aqueous extract of the seeds of Nyctanthes arbor-tristis (aka night jasmine) is very efficient for the synthesis of stable AgNPs from aqueous solution of AgNO3. The extract acts as both reducing (from Ag+ to Ag0) and capping agent in the aqueous phase. The constituents in extract are mainly biomolecules like carbohydrates and phenolic compounds, which are responsible for the preparation of stable AgNPs within 20 min of reaction time at 25 °C using without any severe conditions. The synthesized silver nanoparticles were characterized with UV-Visible spectroscopy, FT-IR, XRD and SEM. UV-Vis spectroscopy analysis showed peak at 420 nm, which corresponds to the surface plasmon resonance of AgNPs. XRD results showed peaks at (111), (200), (220), which confirmed the presence of AgNPs with face-centered cubic structure. The uniform spherical nature of the AgNPs and size (between 50 and 80 nm) were further confirmed by SEM analysis.

Template-Free Synthesis and Enhanced Photocatalytic Performance of Uniform BiOCI Flower-Like Microspheres.

PubMed

Chang, Fei; Xie, Yunchao; Chen, Juan; Luo, Jieru; Li, Chenlu; Hu, Xuefeng; Xu, Bin

2015-02-01

Preparation of uniform BiOCI flower-like microspheres was facilely accomplished through a sim- ple protocol involving regulation of pH value in aqueous with sodium hydroxide in the presence of n-propanol. The as-prepared samples were characterized by a collection of techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), and nitrogen adsorption-desorption isotherms. Based upon the SEM analyses, uniform microspheres could be formed with coexistence of some fragments of BiOCI nanosheets without n-propanol. The addition of appropriate amount of n-propanol was beneficial to provide BiOCI samples containing only flower-like microspheres, which were further subjected to the photocatalytic measurements towards Rhodamine B in aqueous under visible light irradiation and exhibited the best catalytic performance among all samples tested. In addition, the photocatalytic process was confirmed to undergo through a photosensitization pathway, in which superoxide radicals (.O-) played critical roles.

Biosynthesis and characterization of ZnO nanoparticles using the aqueous leaf extract of Imperata cylindrica L.

NASA Astrophysics Data System (ADS)

Saputra, I. S.; Yulizar, Y.

2017-04-01

ZnO nanoparticles (ZnO NPs) were biosynthesized.The growth was observed by a sol-gel method. ZnO were successfully formed through the reaction of zinc nitrate tetrahydrate Zn(NO3)2.4H2O precursor with aqueous leaf extract of Imperata cylindrica L (ICL). The structural and optical properties of ZnO were investigated. The as-synthesized products were characterized by UV-Visible (UV-Vis), UV diffuse reflectance spectroscopy (UV-DRS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). UV-Vis absorption data showed hydrolysis and characteristic of absorption peak at 300 nm of Zn(OH)2. UV-DRS confirmed that ZnO NPs has the indirect band gap at 3.13 eV. FTIR spectrum revealed the functional groups and indicated the presence of protein as the capping and stabilizing agent on the ZnO surface. Powder XRD studies indicated the formation of pure wurtzite hexagonal structure with particle size of 11.9 nm. The detailed morphological and structural characterizations revealed that the synthesized products were hexagonal nanochip.

Visible light assisted photodecolorization of eosin-Y in aqueous solution using hesperidin modified TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Vignesh, K.; Suganthi, A.; Rajarajan, M.; Sakthivadivel, R.

2012-03-01

Hesperidin a flavanoid, modified TiO2 nanoparticles (Hes-TiO2) was synthesized to improve the visible light driven photocatalytic performance of TiO2. The synthesized nanoparticles were characterized by UV-visible diffuse reflectance spectroscopy (UV-vis-DRS), FT-IR, powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activity of Hes-TiO2 was investigated based on the decolorization of eosin-Y under visible light irradiation. Hes-TiO2 showed high efficiency for the decolorization of eosin-Y. The influences of various reaction parameters like effect of pH, catalyst dosage and initial dye concentration on the photocatalytic efficiency were investigated. The adsorption of eosin-Y on Hes-TiO2 was found favorable by the Langmuir approach. The removal percentage of chemical oxygen demand (COD) was determined to evaluate the mineralization of eosin-Y during photodecolorization. Based on the intermediates obtained in the GC-MS spectroscopic technique, a probable degradation mechanism has been proposed.

Temperature characterization of dielectric permittivity and AC conductivity of nano copper oxide-doped polyaniline composite

NASA Astrophysics Data System (ADS)

Shubha, L. N.; Madhusudana Rao, P.

2016-06-01

The polyaniline/copper oxide (PANI/CuO) nanocomposite was prepared by mixing solutions of polyaniline and copper oxide nanoparticles in dimethyl sulfoxide (DMSO). The synthesized polymer nanocomposites were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and UV-visible spectroscopy. The characteristic peaks in XRD and UV-visible spectra confirmed the presence of CuO in the polymer structure. SEM images indicated morphological changes in the composite matrix as compared to the pristine PANI. The DC conductivity measurements were performed using two-probe method for various temperatures. AC conductivity and dielectric response of the composites were investigated in the frequency range of 102-106Hz using LCR meter. Dielectric permittivity ɛ‧(w) and dielectric loss factor ɛ‧‧(w) were investigated. It was observed that ɛ‧(w) and ɛ‧‧(w) decrease with increase in frequency at all temperatures. At a particular frequency it is observed that both ɛ‧(w) and ɛ‧‧(w) increase with increase in temperature. It was also observed that AC conductivity increased with increase in frequency and temperature.

The fabrication of visible light responsive Ag-SiO2 co-doped TiO2 thin films by the sol-gel method

NASA Astrophysics Data System (ADS)

Dam Le, Duy; Dung Dang, Thi My; Thang Chau, Vinh; Chien Dang, Mau

2010-03-01

In this study we have successfully deposited Ag-SiO2 co-doped TiO2 thin films on glass substrates by the sol-gel method. After being coated by a dip coating method, the film was transparent, smooth and had strong adhesion on the glass surface. The deposited film was characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), a scanning electron microscope (SEM) and atomic force microscope (AFM) to investigate its crystallization, transmittance and surface structure. The antifogging ability is explained by the contact angle of water on the surface of the glass substrates under visible-light. The obtained results show that Ag-SiO2 co-doped TiO2 film has potential applications for self cleaning and anti-bacterial ceramic tiles.

Electrodeposition of gold nanoparticles on mesoporous TiO{sub 2} photoelectrode to enhance visible region photocurrent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Supriyono,; Krisnandi, Yuni Krisyuningsih; Gunlazuardi, Jarnuzi, E-mail: jarnuzi@ui.ac.id

2016-04-19

Electrodeposition of gold nanoparticles (Au NPs) on the mesoporous TiO{sub 2} photoelectrode to enchance visible region photocurrent have been investigated. Mesoporous TiO{sub 2} was prepared by a sol gel method and immobilized to the fluorine doped tin oxide (FTO) substrate by dip coating technique. Gold nanoparticles were electrodeposited on the TiO{sub 2} surface and the result FTO/TiO{sub 2}/Au was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), UV-Vis diffuse reflectance spectroscopy (DRS), and X-ray diffraction (XRD). The generated photocurrent was evaluated with an electrochemical workstation (e-DAQ/e-recorder 401) using 60 W wolfram lamp as visible lightmore » source. The photoelectrochemical evaluation indicated that the presence of gold nanoparticles on TiO{sub 2} photoelectrode shall enhance the photocurrent up to 50%.« less

To study the effect of doping concentration of silver on structural and optical properties of cadmium oxide (CdO) nanostructure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Rajesh, E-mail: rkkaushik06@gmail.com; Dept. of Physics, Vaish College of Engineering, Rohtak-124001, Haryana; Sharma, Ashwani

The present work deals with study of structural and optical properties of Silver (Ag) doped Cadmium oxide (CdO) nanostructured synthesized by Chemical Co-precipitation Techniques followed by calcinations at small temperature. The doping concentrations were changing from 0.1 to 10 at% respectively. Structural analysis study of these calcined materials is carried out by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The optical properties of calcined samples were investigating by Fourier transformation infrared (FTIR)spectroscopy, UV-Visible Spectroscopy (UV-Vis). The structural properties analysis results revels that crystallite size are in the range of nano region and TEM results aremore » quite in accordance with XRD results.« less

Phonon shift in chemically exfoliated WS2 nanosheet

NASA Astrophysics Data System (ADS)

Sarkar, Abdus Salam; Pal, Suman Kalyan

2018-04-01

We have synthesized few layer WS2 nanosheets in a low boiling point solvent. Few layer of WS2 sheets are characterized by various techniques such as UV-visible and Raman spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and scanning electron microscopy (SEM). UV-Vis absorption spectra confirm the well dispersed in isopropyl alcohol. SEM and TEM images indicate the sheet like morphology of WS2. Atomic force microscopy image and room temperature Raman spectroscopy confirm the exfoliation of few layer (4-5 layer) of WS2. Further, Raman spectroscopy was used as a meteorology tool to determine the temperature co-efficient. We have systematically investigated the temperature dependent Raman spectroscopic behavior of few layer WS2. Our results depict the softening of the Raman modes E12g in plane vibration and A1g out of plane vibration with increasing the temperature from 77 K to 300 K. Softening of the Raman modes could be explained in terms of the double resonance which is active in the layered materials. The observed temperature coefficients for two Raman peaks E12g and A1g, are - 0.022 cm-1 and -0.009 cm-1, respectively.

A facile method for synthesis of graphene-coated hexagonal ZnO photocatalyst with enhanced photodegradation activity

NASA Astrophysics Data System (ADS)

Zhang, Yunlong; Zhang, Yuzhi

2017-12-01

A kind of hexagonal ZnO (HZO) was synthesized in N-methyl-2-pyrrolidone (NMP)/H2O mixed solvent for a high exposure of polar ±(0001) facets to get a high-efficiency photocatalyst. The amine-functionalized HZO particles were coated with graphene oxide (GO) by electrostatic force-induced self-assemby and thermal reduction to form HZO@Gr core/shell structure. The as-prepared HZO and HZO@Gr were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and UV-visible diffuse reflectance spectroscopy (UV-vis/DRS). The results indicate that the graphene on HZO@Gr remains high quality and the optical properties of the composite change a lot with sunlight absorption improving, bandgap and photoluminescence (PL) intensity decreasing. The obtained HZO photocatalyst shows good photocatalytic activity for methylene blue (MB) under UV-visible irradiation. Furthermore, the HZO@Gr photocatalyst exhibits the best photodegradation rate of MB reaching up to 98.2% within 50 minutes. The graphene-coated HZO structure could offer new directions which would further extend the scope for synthesis of various ZnO/graphene composites with improved properties useful for various applications.

Tuning the optical properties of ZnO nanorods by variation of precursor concentration through hydrothermal method

NASA Astrophysics Data System (ADS)

Kumari, Lakshmi; Kar, Asit Kumar

2018-05-01

ZnO nanorods with varying precursor concentration have been successfully synthesized by the hydrothermal method. The effect of the precursor concentration on the structural, morphological and optical properties of the resulting nanorods was investigated by means of X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), UV-Vis spectroscopy and photoluminescence (PL) spectroscopy. The crystalline structural characterization demonstrated that the synthesized materials crystallize in pure ZnO wurtzite structure without any other secondary phase. SEM micrographs demonstrate nanorod type features in all the samples. In addition, they show that increase of precursor concentration changes the length and diameter of nanorods. The UV-Vis studies show a strong absorption band in UV region at 373 nm attributed to the band-edge absorption of wurtzite hexagonal ZnO, blue shifted relative to its bulk form (380 nm). The PL spectra of obtained nanorods excited at 360 nm present broad visible emission. Moreover, as the visible region (from 510 to 550 nm) is concerned, it is speculated that the increase of the precursor concentration affects strongly the kind of interstitial defects (Oi, Zni and Vo) formed in ZnO nanorods. The luminescence intensity decreases with the increase of precursor concentration.

Transparent nanostructured Fe-doped TiO2 thin films prepared by ultrasonic assisted spray pyrolysis technique

NASA Astrophysics Data System (ADS)

Rasoulnezhad, Hossein; Hosseinzadeh, Ghader; Ghasemian, Naser; Hosseinzadeh, Reza; Homayoun Keihan, Amir

2018-05-01

Nanostructured TiO2 and Fe-doped TiO2 thin films with high transparency were deposited on glass substrate through ultrasonic-assisted spray pyrolysis technique and were used in the visible light photocatalytic degradation of MB dye. The resulting thin films were characterized by scanning electron microscopy (SEM), Raman spectroscopy, photoluminescence spectroscopy, x-ray diffraction (XRD), and UV-visible absorption spectroscopy techniques. Based on Raman spectroscopy results, both of the TiO2 and Fe-doped TiO2 films have anatase crystal structure, however, because of the insertion of Fe in the structure of TiO2 some point defects and oxygen vacancies are formed in the Fe-doped TiO2 thin film. Presence of Fe in the structure of TiO2 decreases the band gap energy of TiO2 and also reduces the electron–hole recombination rate. Decreasing of the electron–hole recombination rate and band gap energy result in the enhancement of the visible light photocatalytic activity of the Fe-doped TiO2 thin film.

Fe(Ⅲ) ions enhanced catalytic properties of (BiO)2CO3 nanowires and mechanism study for complete degradation of xanthate.

PubMed

Guo, Yujiao; Cui, Kuixin; Hu, Mingyi; Jin, Shengming

2017-08-01

The wire-like Fe 3+ -doped (BiO) 2 CO 3 photocatalyst was synthesized by a hydrothermal method. The photocatalytic property of Fe 3+ -doped (BiO) 2 CO 3 nanowires was evaluated through degradation of sodium isopropyl xanthate under UV-visible light irradiation. The as-prepared Fe 3+ -doped (BiO) 2 CO 3 nanowires were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) in detail. The results of XRD showed that the crystallinity of (BiO) 2 CO 3 nanowires decreased when Fe 3+ ions were introduced into the solution system. XPS results illustrated that xanthate could be absorbed on the surface of Fe 3+ -doped (BiO) 2 CO 3 nanowires to produce BiS bond at the beginning of the reaction, which could broaden the visible light absorption. FTIR spectra confirmed the formation of SO 4 2- after photocatalytic decomposition of xanthate solution. The Fe 3+ -doped (BiO) 2 CO 3 nanowires showed an enhanced photocatalytic activity for decomposition of xanthate due to the narrower band gap and larger BET surface area, comparing with pure (BiO) 2 CO 3 nanowires. By the results of UV-vis spectra of the solution and FTIR spectra of recycled Fe 3+ -doped (BiO) 2 CO 3 , the xanthate was oxidized completely into CO 2 and SO 4 2- . The photocatalytic degradation process of xanthate followed a pseudo-second-order kinetics model. The mechanism of enhanced photocatalytic activity was proposed as well. Copyright © 2017 Elsevier Ltd. All rights reserved.

Investigation of polypyrrole/polyvinyl alcohol-titanium dioxide composite films for photo-catalytic applications

NASA Astrophysics Data System (ADS)

Cao, Shaoqiang; Zhang, Hongyang; Song, Yuanqing; Zhang, Jianling; Yang, Haigang; Jiang, Long; Dan, Yi

2015-07-01

Polypyrrole/polyvinyl alcohol-titanium dioxide (PPy/PVA-TiO2) composite films used as photo-catalysts were fabricated by combining TiO2 sol with PPy/PVA solution in which PPy was synthesized by in situ polymerization of pyrrole (Py) in polyvinyl alcohol (PVA) matrix and loaded on glass. The prepared photo-catalysts were investigated by X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra and photoluminescence (PL). The results indicate that the composites have same crystal structure as the TiO2 and extend the optic absorption from UV region to visible light region. By detecting the variation ratio, detected by ultraviolet-vis spectroscopy, of model pollutant rhodamine B (RhB) solution in the presence of the composite films under both UV and visible light irradiation, the photo-catalytic performance of the composite films was investigated. The results show that the PPy/PVA-TiO2 composite films show better photo-catalytic properties than TiO2 film both under UV and visible light irradiation, and the photo-catalytic degradation of RhB follows the first-order kinetics. The effects of the composition of composite films and the concentration of RhB on the photo-catalytic performance, as well as the possible photo-catalytic mechanism, were also discussed. By photo-catalytic recycle experiments, the structure stability of the PPy/PVA-TiO2 composite film was investigated and the results show that the photo-catalytic activity under both UV and visible light irradiation have no significant decrease after four times of recycle experiments, suggesting that the photo-catalyst film is stable during the photo-catalytic process, which was also confirmed by the XRD pattern and FT-IR spectra of the composite film before and after photo-catalytic.

Synthesis of silver nanoparticles from stem bark of Cochlospermum religiosum (L.) Alston: an important medicinal plant and evaluation of their antimicrobial efficacy

NASA Astrophysics Data System (ADS)

Sasikala, A.; Linga Rao, M.; Savithramma, N.; Prasad, T. N. V. K. V.

2015-10-01

The use of different parts of plants for the synthesis of nanoparticles is considered as a green technology as it does not involve any harmful chemicals. Herein, we report on rapid biosynthesis of silver nanoparticles (SNPs) from aqueous stem bark extract of Cochlospermum religiosum a medicinal plant. The reduced silver nanoparticles were characterized by using UV-Visible spectroscopy (UV-Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis, atomic force microscopy, and Fourier transform infrared (FT-IR). The UV-Visible spectrum of the aqueous medium containing silver nanoparticles showed an absorption peak at around 445 nm, XRD showed that the particles are crystalline in nature, with a face-centered cubic structure and the SEM images showed that the spherical-shaped silver nanoparticles were observed and the size range was found to be 20-35 nm. FT-IR spectroscopy analysis revealed that carbohydrate, polyphenols, and protein molecules were involved in the synthesis and capping of silver nanoparticles. These phytosynthesized SNPs were tested for their antimicrobial activity and it analyzed by measuring the inhibitory zone. Cochlospermum religiosum aqueous stem bark extract of SNPs showed highest toxicity to Staphylococcus followed by Pseudomonas, Escherichia coli and Bacillus and lowest toxicity towards Proteus. Whereas in fungal species highest inhibition zone against Aspergillus flavus followed by Rhizopus, Fusarium, and Curvularia, and minimum inhibition zone was observed against Aspergillus niger species. The outcome of this study could be useful for the development of value added products from indigenous medicinal plants of India for nanotechnology-based biomedical applications.

Studies on the thermal and electrical properties of polyethylene oxide/polyvinyl alcohol blend by incorporating of Cesium Chloride

NASA Astrophysics Data System (ADS)

Ragab, H. M.

The composites PVA/PEO filled with various concentrations of CsCl samples, which were prepared for using a solvent casting technique and studied via Fourier transform infrared spectroscopy (FTIR), ultraviolet - visible (UV-Vis), X-ray spectroscopy, Scanning electron microscopy (SEM), AC conductivity and dielectric properties to use as sensor in electronic devices. The FTIR indicated the interaction between PVA/PEO and CsCl. From data of UV. Vis. was observed band gap (Eg) reduces with addition CsCl to polymer blend. The XRD shows the degree of crystallinity (χ%) decreasing with increasing concentration of CsCl from 2.93 to 2.45. The SEM of the surface of composite PVA/PEO filled with various concentrations of CsCl in magnification 1500 times its change with compare of pure blend. From TGA was observed improvement in the thermal stability of the samples after addition of CsCl. The AC conductivity rise more rapidly with temperature and associated with activation energy Ea, for conduction and enhanced with increasing both temperature and frequency.

Green Synthesis of Novel Polyaniline Nanofibers: Application in pH Sensing.

PubMed

Tanwar, Shivani; Ho, Ja-an Annie

2015-10-13

An optically active polyaniline nanomaterial (PANI-Nap), doped with (S)-naproxen, was developed and evaluated as a potent pH sensor. We synthesized the material in one pot by the addition of the dopant, (S)-naproxen, prior to polymerization, followed by the addition of the oxidizing agent (ammonium persulfate) that causes polymerization of the aniline. This green chemistry approach allowed us to take only 1 h to produce a water-soluble and stable nanomaterial. UV-visible spectroscopy, fluorescence spectroscopy, FT-IR spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the designed nanomaterial. This nanomaterial exhibited excellent pH sensing properties and showed long term stability (up to one month) without loss of sensor performance.

Green engineering of biomolecule-coated metallic silver nanoparticles and their potential cytotoxic activity against cancer cell lines

NASA Astrophysics Data System (ADS)

Prasannaraj, Govindaraj; Venkatachalam, Perumal

2017-06-01

This report describes the synthesis of metallic silver nanoparticles (AgNPs) using extracts of four medicinal plants (Aegle marmelos (A. marmelos), Alstonia scholaris (A. scholaris), Andrographis paniculata (A. paniculata) and Centella asiatica (C. asiatica)). The bio-conjugates were characterized by UV-visible spectroscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared spectrometry (FTIR), x-ray diffraction (XRD) and zeta potential. This analysis confirmed that UV-Vis spectral peaks at 375 nm, 380 nm, 420 nm and 380 nm are corresponding to A. marmelos, A. scholaris, A. paniculata and C. asiatica mediated AgNPs, respectively. SEM images revealed that all the obtained four AgNPs are predominantly spherical, fibres and rectangle in shape with an average size of 36-97 nm. SEM-EDS and XRD analysis confirmed the presence of elemental AgNPs in crystalline form for all the four nanoparticle samples. The phytochemicals of various medicinal plant extracts with different functional groups were responsible for reduction of Ag+ to AgNPs, which act as capping and stabilizing agent. Among four types of AgNPs tested for anticancer activity, the Ap mediated AgNPs had shown enhanced activity against HepG2 cells (27.01 µg ml-1) and PC3 cells (32.15 µg ml-1).

Memecylon edule leaf extract mediated green synthesis of silver and gold nanoparticles

PubMed Central

Elavazhagan, Tamizhamudu; Arunachalam, Kantha D

2011-01-01

We used an aqueous leaf extract of Memecylon edule (Melastomataceae) to synthesize silver and gold nanoparticles. To our knowledge, this is the first report where M. edule leaf broth was found to be a suitable plant source for the green synthesis of silver and gold nanoparticles. On treatment of aqueous solutions of silver nitrate and chloroauric acid with M. edule leaf extract, stable silver and gold nanoparticles were rapidly formed. The gold nanoparticles were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX) and Fourier transform infra-red spectroscopy (FTIR). The kinetics of reduction of aqueous silver and gold ions during reaction with the M. edule leaf broth were easily analyzed by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to M. edule leaf broth, were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20–50 nm. TEM analysis of gold nanoparticles showed formation of triangular, circular, and hexagonal shapes in the size range 10–45 nm. The resulting silver nanoparticles were predominantly square with uniform size range 50–90 nm. EDAX results confirmed the presence of triangular nanoparticles in the adsorption peak of 2.30 keV. Further FTIR analysis was also done to identify the functional groups in silver and gold nanoparticles. The characterized nanoparticles of M. edule have potential for various medical and industrial applications. Saponin presence in aqueous extract of M. edule is responsible for the mass production of silver and gold nanoparticles. PMID:21753878

Memecylon edule leaf extract mediated green synthesis of silver and gold nanoparticles.

PubMed

Elavazhagan, Tamizhamudu; Arunachalam, Kantha D

2011-01-01

We used an aqueous leaf extract of Memecylon edule (Melastomataceae) to synthesize silver and gold nanoparticles. To our knowledge, this is the first report where M. edule leaf broth was found to be a suitable plant source for the green synthesis of silver and gold nanoparticles. On treatment of aqueous solutions of silver nitrate and chloroauric acid with M. edule leaf extract, stable silver and gold nanoparticles were rapidly formed. The gold nanoparticles were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX) and Fourier transform infra-red spectroscopy (FTIR). The kinetics of reduction of aqueous silver and gold ions during reaction with the M. edule leaf broth were easily analyzed by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to M. edule leaf broth, were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20-50 nm. TEM analysis of gold nanoparticles showed formation of triangular, circular, and hexagonal shapes in the size range 10-45 nm. The resulting silver nanoparticles were predominantly square with uniform size range 50-90 nm. EDAX results confirmed the presence of triangular nanoparticles in the adsorption peak of 2.30 keV. Further FTIR analysis was also done to identify the functional groups in silver and gold nanoparticles. The characterized nanoparticles of M. edule have potential for various medical and industrial applications. Saponin presence in aqueous extract of M. edule is responsible for the mass production of silver and gold nanoparticles.

Chrysopogon zizanioides aqueous extract mediated synthesis, characterization of crystalline silver and gold nanoparticles for biomedical applications

PubMed Central

Arunachalam, Kantha D; Annamalai, Sathesh Kumar

2013-01-01

The exploitation of various plant materials for the biosynthesis of nanoparticles is considered a green technology as it does not involve any harmful chemicals. The aim of this study was to develop a simple biological method for the synthesis of silver and gold nanoparticles using Chrysopogon zizanioides. To exploit various plant materials for the biosynthesis of nanoparticles was considered a green technology. An aqueous leaf extract of C. zizanioides was used to synthesize silver and gold nanoparticles by the bioreduction of silver nitrate (AgNO3) and chloroauric acid (HAuCl4) respectively. Water-soluble organics present in the plant materials were mainly responsible for reducing silver or gold ions to nanosized Ag or Au particles. The synthesized silver and gold nanoparticles were characterized by ultraviolet (UV)-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analysis. The kinetics decline reactions of aqueous silver/gold ion with the C. zizanioides crude extract were determined by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to the extract were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20–50 nm. This eco-friendly approach for the synthesis of nanoparticles is simple, can be scaled up for large-scale production with powerful bioactivity as demonstrated by the synthesized silver nanoparticles. The synthesized nanoparticles can have clinical use as antibacterial, antioxidant, as well as cytotoxic agents and can be used for biomedical applications. PMID:23861583

Room-temperature synthesis and photoluminescence of hexagonal CePO4 nanorods

NASA Astrophysics Data System (ADS)

Zhu, J.; Zhang, K.; Zhao, H. Y.

2018-01-01

Hexagonal CePO4 nanorods were synthesized via a simple chemical precipitation route at room-temperature without the presence of surfactants and then characterized by powder X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectrometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption and photoluminescence (PL) spectroscopy. Hexagonal CePO4 nanorods exhibit strong ultraviolet absorption and ultraviolet luminescence, which correspond to the electronic transitions between 4f and 5d state of Ce3+ ions.

Catalytic degradation of Amlodipine Besylate using ZnO, Cu doped ZnO, and Fe doped ZnO nanoparticles from an aqueous solution: Investigating the effect of different parameters on degradation efficiency

NASA Astrophysics Data System (ADS)

Alizadeh, Elahe; Baseri, Hadi

2018-04-01

Some common nanoparticles, such as Zinc Oxide have been used as nanocatalysts in many processes, but they also have an important application in water purification processes. In this research, ZnO based nanoparticles were used for the degradation of Amlodipine Besylate (AMB) and the effect of some main parameters, e.g. initial concentration of AMB, nanocatalysts dose, pH of the solution, temperature of the solution, H2O2 dose, and the time of visible light irradiation, were investigated. The destruction amount was determined by UV-Vis spectroscopy. The synthesized nanoparticles were characterized by FE-SEM, XRD, FT-IR, BET, BJH, EDS, XRF and UV-Vis techniques. The maximum degradation of AMB was about 90% in 60 min of visible light irradiation with 100 μL of H2O2.

Simple route to (NH4)xWO3 nanorods for near infrared absorption

NASA Astrophysics Data System (ADS)

Guo, Chongshen; Yin, Shu; Dong, Qiang; Sato, Tsugio

2012-05-01

Described here is how to synthesize one-dimensional ammonium tungsten bronze ((NH4)xWO3) by a facile solvothermal approach in which ethylene glycol and acetic acid were employed as solvents and ammonium paratungstate was used as a starting material, as well as how to develop the near infrared absorption properties of (NH4)xWO3 nanorods for application as a solar light control filter. The as-obtained product was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), atomic force microscope (AFM) and UV-Vis-NIR spectra. The SEM and TEM images clearly revealed that the obtained sample possessed rod/fiber-like morphologies with diameters around 120 nm. As determined by UV-Vis-NIR optical measurement, the thin film consisted of (NH4)xWO3 nanoparticles, which can selectively transmit most visible lights, but strongly absorb the near-infrared (NIR) lights and ultraviolet rays. These interesting optical properties make the (NH4)xWO3 nanorods suitable for the solar control windows.Described here is how to synthesize one-dimensional ammonium tungsten bronze ((NH4)xWO3) by a facile solvothermal approach in which ethylene glycol and acetic acid were employed as solvents and ammonium paratungstate was used as a starting material, as well as how to develop the near infrared absorption properties of (NH4)xWO3 nanorods for application as a solar light control filter. The as-obtained product was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), atomic force microscope (AFM) and UV-Vis-NIR spectra. The SEM and TEM images clearly revealed that the obtained sample possessed rod/fiber-like morphologies with diameters around 120 nm. As determined by UV-Vis-NIR optical measurement, the thin film consisted of (NH4)xWO3 nanoparticles, which can selectively transmit most visible lights, but strongly absorb the near-infrared (NIR) lights and ultraviolet rays. These interesting optical properties make the (NH4)xWO3 nanorods suitable for the solar control windows. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30612c

Synthesis of novel CeO2-BiVO4/FAC composites with enhanced visible-light photocatalytic properties.

PubMed

Zhang, Jin; Wang, Bing; Li, Chuang; Cui, Hao; Zhai, Jianping; Li, Qin

2014-09-01

To utilize visible light more effectively in photocatalytic reactions, a fly ash cenosphere (FAC)-supported CeO2-BiVO4 (CeO2-BiVO4/FAC) composite photocatalyst was prepared by modified metalorganic decomposition and impregnation methods. The physical and photophysical properties of the composite have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and UV-Visible diffuse reflectance spectra. The XRD patterns exhibited characteristic diffraction peaks of both BiVO4 and CeO2 crystalline phases. The XPS results showed that Ce was present as both Ce(4+) and Ce(3+) oxidation states in CeO2 and dispersed on the surface of BiVO4 to constitute a p-n heterojunction composite. The absorption threshold of the CeO2-BiVO4/FAC composite shifted to a longer wavelength in the UV-Vis absorption spectrum compared to the pure CeO2 and pure BiVO4. The composites exhibited enhanced photocatalytic activity for Methylene Blue (MB) degradation under visible light irradiation. It was found that the 7.5wt.% CeO2-BiVO4/FAC composite showed the highest photocatalytic activity for MB dye wastewater treatment. Copyright © 2014. Published by Elsevier B.V.

CdSe nanorod/TiO2 nanoparticle heterojunctions with enhanced solar- and visible-light photocatalytic activity.

PubMed

Laatar, Fakher; Moussa, Hatem; Alem, Halima; Balan, Lavinia; Girot, Emilien; Medjahdi, Ghouti; Ezzaouia, Hatem; Schneider, Raphaël

2017-01-01

CdSe nanorods (NRs) with an average length of ≈120 nm were prepared by a solvothermal process and associated to TiO 2 nanoparticles (Aeroxide ® P25) by annealing at 300 °C for 1 h. The content of CdSe NRs in CdSe/TiO 2 composites was varied from 0.5 to 5 wt %. The CdSe/TiO 2 heterostructured materials were characterized by XRD, TEM, SEM, XPS, UV-visible spectroscopy and Raman spectroscopy. TEM images and XRD patterns show that CdSe NRs with wurtzite structure are associated to TiO 2 particles. The UV-visible spectra demonstrate that the narrow bandgap of CdSe NRs serves to increase the photoresponse of CdSe/TiO 2 composites until ≈725 nm. The CdSe (2 wt %)/TiO 2 composite exhibits the highest photocatalytic activity for the degradation of rhodamine B in aqueous solution under simulated sunlight or visible light irradiation. The enhancement in photocatalytic activity likely originates from CdSe sensitization of TiO 2 and the heterojunction between these materials which facilitates electron transfer from CdSe to TiO 2 . Due to its high stability (up to ten reuses without any significant loss in activity), the CdSe/TiO 2 heterostructured catalysts show high potential for real water decontamination.

Poly (N-ethyl aniline)/Ag Nanocomposite as Humidity Sensor

NASA Astrophysics Data System (ADS)

Pande, Nishigandh S.; Jaspal, Dipika; Ambekar, Jalindar

Poly (N-ethyl aniline)/Ag organic-inorganic composite has been synthesized by a single step in situ chemical oxidative polymerization method. The synthesis of Poly (N-ethyl aniline)/Ag nanocomposite has been confirmed by X-ray diffraction (XRD), Ultraviolet-Vis Spectroscopy (UV-visible), Fourier transform infrared analysis (FTIR) and FE-SEM investigations. XRD spectral study exhibited major diffraction in the range 20-80∘ (2θ) and indicated the semicrystalline nature of poly (N-ethyl aniline)/Ag nanocomposite. Characteristic peaks in UV-visible and FTIR spectra of poly (N-ethyl aniline) switched to higher wave numbers in poly (N-ethyl aniline)/Ag nanocomposite. Peaks at 1789cm-1, 1595cm-1, 667cm-1 and 501cm-1 in FTIR spectrum confirmed the formation of poly (N-ethyl aniline)/Ag nanocomposite. FE-SEM photographs reported agglomerated granular particulate nature of poly (N-ethyl aniline)/Ag nanocomposite. Synthesized poly (N-ethyl aniline)/Ag nanocomposite exhibited a high response to humidity, good reproducibility and stability at room temperature. An appreciable response was shown in the presence of 40% humid atmosphere for up to successive four cycles. Composite sensitivity has been found to increase with the increasing concentration of humidity, at room temperature.

Eco-friendly synthesis of cuprous oxide (Cu2O) nanoparticles and improvement of their solar photocatalytic activities

NASA Astrophysics Data System (ADS)

Kerour, A.; Boudjadar, S.; Bourzami, R.; Allouche, B.

2018-07-01

In this work, we have synthesized cuprous oxide (Cu2O) nanoparticles with octahedral and spherical like shapes by an ecofriendly, simple and coast effective method, by using the aqueous extract of Aloe vera and copper sulfate as solvent and precursor respectively. The effect of Aloe vera aqueous extract concentration on the morphological, structural and optical properties of as synthesized nanoparticles was studied by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform (FT-IR) spectroscopy and UV-visible diffuse reflectance. The SEM images showing octahedral and spherical agglomeration of nanoparticles. The cubic structure of Cu2O was confirmed by XRD analysis, the crystallites size depends to the concentration of Aloe vera aqueous extract with an average size ranged between 24 and 61 nm. The FT-IR vibration measurements valid the presence of pure Cu2O in the samples. The UV-visible spectra show that the prepared cuprous oxide (Cu2O) has a gap energy estimated from 2.5 to 2.62 eV. The photocatalytic activities of the as-prepared material were highly improvement by the fast degradation of methylene blue in aqueous solution at room temperature under solar simulator irradiation.

Chemometric classification of Chinese lager beers according to manufacturer based on data fusion of fluorescence, UV and visible spectroscopies.

PubMed

Tan, Jin; Li, Rong; Jiang, Zi-Tao

2015-10-01

We report an application of data fusion for chemometric classification of 135 canned samples of Chinese lager beers by manufacturer based on the combination of fluorescence, UV and visible spectroscopies. Right-angle synchronous fluorescence spectra (SFS) at three wavelength difference Δλ=30, 60 and 80 nm and visible spectra in the range 380-700 nm of undiluted beers were recorded. UV spectra in the range 240-400 nm of diluted beers were measured. A classification model was built using principal component analysis (PCA) and linear discriminant analysis (LDA). LDA with cross-validation showed that the data fusion could achieve 78.5-86.7% correct classification (sensitivity), while those rates using individual spectroscopies ranged from 42.2% to 70.4%. The results demonstrated that the fluorescence, UV and visible spectroscopies complemented each other, yielding higher synergic effect. Copyright © 2015 Elsevier Ltd. All rights reserved.

Facile green synthesis of silver nanoparticles using seed aqueous extract of Pistacia atlantica and its antibacterial activity

NASA Astrophysics Data System (ADS)

Sadeghi, Babak; Rostami, Amir; Momeni, S. S.

2015-01-01

In the present work, we describe the synthesis of silver nanoparticles (Ag-NPs) using seed aqueous extract of Pistacia atlantica (PA) and its antibacterial activity. UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray energy dispersive spectrophotometer (EDAX) were performed to ascertain the formation of Ag-NPs. It was observed that the growths of Ag-NPs are stopped within 35 min of reaction time. The synthesized Ag-NPs were characterized by a peak at 446 nm in the UV-visible spectrum. XRD confirmed the crystalline nature of the nanoparticles of 27 nm size. The XRD peaks at 38°, 44°, 64° and 77° can be indexed to the (1 1 1), (2 0 0), (2 2 0) and (3 1 1) Bragg's reflections of cubic structure of metallic silver, respectively. The FTIR result clearly showed that the extracts containing OH as a functional group act in capping the nanoparticles synthesis. Antibacterial activities of Ag-NPs were tested against the growth of Gram-positive (S. aureus) using SEM. The inhibition was observed in the Ag-NPs against S. aureus. The results suggest that the synthesized Ag-NPs act as an effective antibacterial agent. It is confirmed that Ag-NPs are capable of rendering high antibacterial efficacy and hence has a great potential in the preparation of used drugs against bacterial diseases. The scanning electron microscopy (SEM), indicated that, the most strains of S. aureus was damaged and extensively disappeared by addition of Ag-NPs. The results confirmed that the (PA) is a very good eco friendly and nontoxic source for the synthesis of Ag-NPs as compared to the conventional chemical/physical methods.

Facile green synthesis of silver nanoparticles using seed aqueous extract of Pistacia atlantica and its antibacterial activity.

PubMed

Sadeghi, Babak; Rostami, Amir; Momeni, S S

2015-01-05

In the present work, we describe the synthesis of silver nanoparticles (Ag-NPs) using seed aqueous extract of Pistacia atlantica (PA) and its antibacterial activity. UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray energy dispersive spectrophotometer (EDAX) were performed to ascertain the formation of Ag-NPs. It was observed that the growths of Ag-NPs are stopped within 35 min of reaction time. The synthesized Ag-NPs were characterized by a peak at 446 nm in the UV-visible spectrum. XRD confirmed the crystalline nature of the nanoparticles of 27 nm size. The XRD peaks at 38°, 44°, 64° and 77° can be indexed to the (111), (200), (220) and (311) Bragg's reflections of cubic structure of metallic silver, respectively. The FTIR result clearly showed that the extracts containing OH as a functional group act in capping the nanoparticles synthesis. Antibacterial activities of Ag-NPs were tested against the growth of Gram-positive (S. aureus) using SEM. The inhibition was observed in the Ag-NPs against S. aureus. The results suggest that the synthesized Ag-NPs act as an effective antibacterial agent. It is confirmed that Ag-NPs are capable of rendering high antibacterial efficacy and hence has a great potential in the preparation of used drugs against bacterial diseases. The scanning electron microscopy (SEM), indicated that, the most strains of S. aureus was damaged and extensively disappeared by addition of Ag-NPs. The results confirmed that the (PA) is a very good eco friendly and nontoxic source for the synthesis of Ag-NPs as compared to the conventional chemical/physical methods. Copyright © 2014 Elsevier B.V. All rights reserved.

Photocatalytic performance of Ag doped SnO2 nanoparticles modified with curcumin

NASA Astrophysics Data System (ADS)

Vignesh, K.; Hariharan, R.; Rajarajan, M.; Suganthi, A.

2013-07-01

Visible light active Ag doped SnO2 nanoparticles modified with curcumin (Cur-Ag-SnO2) have been prepared by a combined precipitation and chemical impregnation route. The optical properties, phase structures and morphologies of the as-prepared nanoparticles were characterized using UV-visible diffuse reflectance spectra (UV-vis-DRS), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The surface area was measured by Brunauer. Emmett. Teller (B.E.T) analysis. Compared to bare SnO2, the surface modified photocatalysts (Ag-SnO2 and Cur-Ag-SnO2) showed a red shift in the visible region. The photocatalytic activity was monitored via the degradation of rose bengal (RB) dye and the results revealed that Cur-Ag-SnO2 shows better photocatalytic activity than that of Ag-SnO2 and SnO2. The superior photocatalytic activity of Cur-Ag-SnO2 could be attributed to the effective electron-hole separation by surface modification. The effect of photocatalyst concentration, initial dye concentration and electron scavenger on the photocatalytic activity was examined in detail. Furthermore, the antifungal activity of the photocatalysts and the reusability of Cur-Ag-SnO2 were tested.

The preparation and photocatalytic activity of CdS/(Cal-Ta2O5-SiO2) composite photocatalyst under visible light

NASA Astrophysics Data System (ADS)

Li, Juxia

2018-02-01

CdS/(Cal-Ta2O5-SiO2) composite photocatalyst has been successfully fabricated via wet chemistry method. Ta2O5-SiO2 with multi-step Ta2O5 deposition on SiO2 has more Ta2O5 on SiO2 to ensure the active sites. Trough multi-step calcination, Ta2O5 can load on SiO2 with uniform and stable, which make it have high photocatalytic activity. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance ultraviolet-visible spectroscopy (UV-vis) and photoluminescence spectroscopy (PL). Without any co-catalysts, the as-prepared CdS/(Cal-Ta2O5-SiO2) exhibited remarkable photocatalytic activity and recyclability both in the degradation of rhodamine B and in the hydrogen production from water splitting under visible light.

Novel high potential visible-light-active photocatalyst of CNT/Mo, S-codoped TiO2 hetero-nanostructure

NASA Astrophysics Data System (ADS)

Hamadanian, M.; Shamshiri, M.; Jabbari, V.

2014-10-01

The current study deals with synthesize of novel nanophotocatalysts of CNT/Mo,S-codoped TiO2 by reacting between titanium isopropoxide (Ti(OC3H7)4) and CNT in aqueous ammonia and subsequent calcining of hydrolysis of the products. The prepared catalysts were characterized by N2 adsorption-desorption measurements, XRD, SEM, TEM, EDX, FT-IR, and UV-vis DRS spectroscopy. SEM and TEM images exhibited uniform coverage of CNT with anatase TiO2 nanoclusters. It was also demonstrated that the presence of S and Mo within the TiO2 acts as electrons traps and prevents the charge recombination and also enables the TiO2 photocatalyst to be active in visible-light region. Moreover, the CNT/Mo,S-doped TiO2 nanohybrids has been proven to has a excellent photocatalytic performance in photodecomposition of Congored (CR), at which the rate of decomposition reaches 100% in only 20 and 30 min under UV and visible-light irradiation, respectively. The enhanced photocatalytic activity was ascribed to the synergetic effects of excellent electrical property of CNT and metal-non-metal codoping. Finally, which to best of our knowledge is done for the first time, we have demonstrated that Mo- and S-doped TiO2 decorated over CNT, or CNT/Mo,S-codoped TiO2, may have high potential applications in photocatalysis and environmental protection with superior catalytic activity under visible-light illumination.

The electrodeposition of multilayers on a polymeric substrate in Flexible Organic Light Emitting Diode (OLED)

NASA Astrophysics Data System (ADS)

Guedes, Andre F. S.; Guedes, Vilmar P.; Tartari, Simone; Cunha, Idaulo Jose

2016-09-01

The development of Organic Light Emitting Diode (OLED), using an optically transparent substrate material and organic semiconductor materials, has been widely utilized by the electronic industry when producing new technological products. The OLED are the base Poly(3,4-ethylenedioxythiophene), PEDOT, Poly(p-phenylenevinylene), PPV, and Polyaniline, PANI, were deposited in Indium Tin Oxide, ITO, and characterized by UV-Visible Spectroscopy (UV-Vis), Optical Parameters (OP) and Scanning Electron Microscopy (SEM). In addition, the thin film obtained by the deposition of PANI, prepared in perchloric acid solution, was identified through PANI-X1. The result obtained by UV-Vis has demonstrated that the PET/ITO/PEDOT/PPV/PANI-X1/Al layer does not have displacement of absorption for wavelengths greaters after spin-coating and electrodeposition. Thus, the spectral irradiance of the OLED informed the irradiance of 100 W/m2, and this result, compared with the standard Light Emitting Diode (LED), has indicated that the OLED has higher irradiance. After 1200 hours of electrical OLED tests, the appearance of nanoparticles visible for images by SEM, to the migration process of organic semiconductor materials, was present, then. Still, similar to the phenomenon of electromigration observed in connections and interconnections of microelectronic devices, the results have revealed a new mechanism of migration, which raises the passage of electric current in OLED.

Nanowires of silver-polyaniline nanocomposite synthesized via in situ polymerization and its novel functionality as an antibacterial agent.

PubMed

Tamboli, Mohaseen S; Kulkarni, Milind V; Patil, Rajendra H; Gade, Wasudev N; Navale, Shalaka C; Kale, Bharat B

2012-04-01

Silver-polyaniline (Ag-PANI) nanocomposite was synthesized by in situ polymerization method using ammonium persulfate (APS) as an oxidizing agent in the presence of dodecylbenzene sulfonic acid (DBSA) and silver nitrate (AgNO(3)). The as synthesized Ag-PANI nanocomposite was characterized by using different analytical techniques such as UV-visible (UV-vis) and Fourier transform Infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), thermo gravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscopy (TEM). UV-visible spectra of the synthesized nanocomposite showed a sharp peak at ~420 nm corresponding to the surface plasmon resonance (SPR) of the silver nanoparticles (AgNPs) embedded in the polymer matrix which is overlapped by the polaronic peak of polyaniline appearing at that wavelength. Nanowires of Ag-PANI nanocomposite with diameter 50-70 nm were observed in FE-SEM and TEM. TGA has indicated an enhanced thermal stability of nanocomposite as compared to that of pure polymer. The Ag-PANI nanocomposite has shown an antibacterial activity against model organisms, a gram positive Bacillus subtilis NCIM 6633 in Mueller-Hinton (MH) medium, which is hitherto unattempted. The Ag-PANI nanocomposite with monodispersed AgNPs is considered to have potential applications in sensors, catalysis, batteries and electronic devices. Copyright © 2011 Elsevier B.V. All rights reserved.

Morphological effect of BiVO4 catalysts on degradation of aqueous paracetamol under visible light irradiation.

PubMed

Hu, Changying; Xu, Jie; Zhu, Yaqi; Chen, Acong; Bian, Zhaoyong; Wang, Hui

2016-09-01

Morphological effect of bismuth vanadate (BiVO4) on visible light-driven catalytic degradation of aqueous paracetamol was carefully investigated using four monoclinic BiVO4 catalysts. The catalysts with different morphologies were controllably prepared by a hydrothermal method without any additions. The prepared catalysts were fully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis diffuse reflectance spectroscopy (DRS). Under the visible light irradiation, these catalysts with different morphology were investigated to degrade aqueous paracetamol contaminant. The degradation effects were evaluated based on the catalyst morphology, solution pH, initial paracetamol concentration, and catalyst dosage. Cube-like BiVO4 powders exhibited excellent photocatalytic performance. The optimal photocatalytic performance of the cube-like BiVO4 in degrading paracetamol was achieved.

Nitrogen Doped Graphene Nickel Ferrite Magnetic Photocatalyst for the Visible Light Degradation of Methylene Blue.

PubMed

Singh, Rajinder; Ladol, Jigmet; Khajuria, Heena; Sheikh, Haq Nawaz

2017-01-01

A facile approach has been devised for the preparation of magnetic NiFe2O4 photocatalyst (NiFe2O4-NG) supported on nitrogen doped graphene (NG). The NiFe2O4-NG composite was synthesized by one step hydrothermal method. The nanocomposite catalyst was characterized by Powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Ultraviolet-visible spectroscopy (UV-Vis) and Vibrating sample magnetometry (VSM). It is found that the combination of NiFe2O4 nanoparticles with nitrogen-doped graphene sheets converts NiFe2O4 into a good catalyst for methylene blue (MB) dye degradation by irradiation of visible light. The catalytic activity under visible light irradiation is assigned to extensive movement of photogenerated electron from NiFe2O4 to the conduction band of the reduced NG, effectively blocking direct recombination of electrons and holes. The NiFe2O4 nanoparticles alone have efficient magnetic property, so can be used for magnetic separation in the solution without additional magnetic support.

Structural characterization of silver nanoparticles phyto-mediated by a plant waste, seed hull of Vigna mungo and their biological applications

NASA Astrophysics Data System (ADS)

Varadavenkatesan, Thivaharan; Vinayagam, Ramesh; Selvaraj, Raja

2017-11-01

Nanobiotechnology has rapidly become a critical facet of nanotechnology. The green synthesis of silver nanoparticles, making use of the hull of black gram (Vigna mungo), paves the way for a simple and eco-friendly utilization of a domestic waste to a product with antioxidant and anticoagulant activities. The emergence of silver nanoparticles was characterized by a variety of methods UV-visible spectrophotometry, scanning electron microscopy added to energy dispersive spectroscopy, X-ray diffractometry, particle size distribution and FT-IR spectroscopy analyses. A discrete band at 421 nm was obtained from UV-visible spectroscopy of the silver nanoparticle suspension. The extract sourced from the hull of black gram showed evidence of the presence of a variety of functional moieties of phytochemicals using FTIR spectroscopy. These were also deemed responsible for maintaining the stability of silver nanoparticles. SEM and EDAX techniques combined, proved that the zero-valent silver nanoparticles were lesser than 100 nm in size. The crystallinity of the nanoparticles was confirmed, as deduced by the (1 1 1) plane, from XRD analysis. The potential of the phytochemicals in maintaining the steadiness of nanoparticles was implied by the zeta potential value that stood at -30.3 mV. In the current study, we have endeavored to comprehend the antioxidant and anticoagulant nature of the green-synthesized benign silver nanoparticles.

Time dependent rise and decay of photocurrent in zinc oxide nanoparticles in ambient and vacuum medium

NASA Astrophysics Data System (ADS)

C, Rajkumar; Srivastava, Rajneesh K.

2018-05-01

Zinc oxide (ZnO) nanoparticle has been synthesized by cost effective Co-precipitation method and studied its photo-response activity. The synthesized ZnO nanomaterial was characterized by using various analytical techniques such as x-ray diffraction (XRD), UV–visible spectroscopy, FTIR spectroscopy, photoluminescence (PL) spectroscopy, and Scanning Electron Microscopy (SEM). From the XRD results, it is confirmed that synthesized ZnO nanomaterial possess hexagonal wurtzite phase structure with an average crystallite size of ∼16–17 nm. The UV-Visible absorption spectrum shows that it has blue shift compared to their bulk counterparts. Photoluminescence spectra of ZnO nanoparticles have a strong violet band at 423 nm and three weak bands at 485 nm (blue), 506 nm (green), and 529 nm (green). The presence of hydroxyl group was confirmed by FTIR. The photo-response analysis was studied by the time-dependent rise and decay photocurrent of ZnO nanoparticle was tested in the air as well as vacuum medium.

Sol-gel synthesis of thorn-like ZnO nanoparticles endorsing mechanical stirring effect and their antimicrobial activities: Potential role as nano-antibiotics

PubMed Central

Khan, Mohd Farhan; Ansari, Akhter H.; Hameedullah, M.; Ahmad, Ejaz; Husain, Fohad Mabood; Zia, Qamar; Baig, Umair; Zaheer, Mohd Rehan; Alam, Mohammad Mezbaul; Khan, Abu Mustafa; AlOthman, Zeid A.; Ahmad, Iqbal; Ashraf, Ghulam Md; Aliev, Gjumrakch

2016-01-01

The effect of mechanical stirring on sol-gel synthesis of thorn-like ZnO nanoparticles (ZnO-NPs) and antimicrobial activities is successfully reported in this study. The in-house synthesized nanoparticles were characterized by XRD, SEM, TEM, FTIR, TGA, DSC and UV-visible spectroscopy. The X-Ray Diffraction analysis revealed the wurtzite crystal lattice for ZnO-NPs with no impurities present. The diametric measurements of the synthesized thorn-like ZnO-NPs (morphology assessed by SEM) were well accounted to be less than 50 nm with the help of TEM. Relative decrease in aspect ratio was observed on increasing the agitation speed. The UV-visible spectroscopy showed the absorption peaks of the ZnO-NPs existed in both UVA and UVB region. A hypsochromic shift in λmax was observed when stirring pace was increased from 500 rpm to 2000 rpm. The FTIR spectroscopy showed the absorption bands of the stretching modes of Zn-O between 500 cm−1 to 525 cm−1. The Thermal analysis studies revealed better stability for ZnO-NPs prepared at 2000 rpm (ZnO-2000 rpm). TGA revealed the weight loss between two main temperatures ranges viz. around (90 °C–120 °C) and (240 °C–280 °C). Finally, the effect of ZnO-NPs prepared at different stirring conditions on the growth of Gram-positive (Bacillus subtilis), Gram-negative (Escherichia coli) bacteria and a fungi (Candida albicans) were examined; which showed good antibacterial as well as antifungal properties. These findings introduce a simple, inexpensive process to synthesize ZnO-NPs using conventional methods without the use of sophisticated equipments and its application as a potent nano-antibiotic. PMID:27349836

UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi.

PubMed

Lando, Gabriela Albara; Marconatto, Letícia; Kessler, Felipe; Lopes, William; Schrank, Augusto; Vainstein, Marilene Henning; Weibel, Daniel Eduardo

2017-07-18

Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU) are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae , when the films were pre-treated with Ultraviolet (UV) irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR), scanning electron microscopy (SEM), and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management.

Facile synthesis of novel CaFe2O4/g-C3N4 nanocomposites for degradation of methylene blue under visible-light irradiation.

PubMed

Vadivel, S; Maruthamani, D; Habibi-Yangjeh, A; Paul, Bappi; Dhar, Siddhartha Sankar; Selvam, Kaliyamoorthy

2016-10-15

Hybrid organic/inorganic nanocomposites comprised of calcium ferrite (CaFe2O4) and graphitic carbon nitride (g-C3N4) were prepared via a simple two-step process. The hybridized CaFe2O4/g-C3N4 heterostructure was characterized by a variety of techniques, including X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDS), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy, electrochemical impedance spectroscopy (EIS), and photoelectrochemical studies. Photocatalytic activity of the prepared samples was evaluated against degradation of methylene blue (MB) under visible-light irradiation. The photocatalytic activity of CaFe2O4 30%/g-C3N4 nanocomposite, as optimum photocatalyst, for degradation of MB was superior to the pure CaFe2O4 and g-C3N4 samples. It was demonstrated that the photogenerated holes and superoxide ion radicals were the two main reactive species towards the photocatalytic degradation of MB over the nanocomposite. Based on the experimental results, a possible photocatalytic mechanism for the MB degradation over the nanocomposite was proposed. This work may provide some inspiration for the fabrication of spinel ferrites with efficient photocatalytic performance. Copyright © 2016 Elsevier Inc. All rights reserved.

Synthesis, characterization and visible-light driven photocatalysis by differently structured CdS/ZnS sandwich and core-shell nanocomposites

NASA Astrophysics Data System (ADS)

Qutub, Nida; Pirzada, Bilal Masood; Umar, Khalid; Mehraj, Owais; Muneer, M.; Sabir, Suhail

2015-11-01

CdS/ZnS sandwich and core-shell nanocomposites were synthesized by a simple and modified Chemical Precipitation method under ambient conditions. The synthesized composites were characterized by XRD, SEM, TEM, EDAX and FTIR. Optical properties were analyzed by UV-vis. Spectroscopy and the photoluminescence study was done to monitor the recombination of photo-generated charge-carriers. Thermal stability of the synthesized composites was analyzed by Thermal Gravimetric Analysis (TGA). XRD revealed the formation of nanocomposites as mixed diffraction peaks were observed in the XRD pattern. SEM and TEM showed the morphology of the nanocomposites particles and their fine particle size. EDAX revealed the appropriate molar ratios exhibited by the constituent elements in the composites and FTIR gave some characteristic peaks which indicated the formation of CdS/ZnS nanocomposites. Electrochemical Impedance Spectroscopy was done to study charge transfer properties along the nanocomposites. Photocatalytic properties of the synthesized composites were monitored by the photocatalytic kinetic study of Acid Blue dye and p-chlorophenol under visible light irradiation. Results revealed the formation of stable core-shell nanocomposites and their efficient photocatalytic properties.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandraboss, V.L.; Natanapatham, L.; Karthikeyan, B.

Graphical abstract: The hetero-junctions that are formed between the ZnO and the Bi provide an internal electric field that facilitates separation of the electron-hole pairs and induces faster carrier migration. Thus they often enhanced photocatalytic reaction. - Highlights: • Bi-doped ZnO nanocomposite material was prepared by precipitation method. • Characterized by XRD, HR-SEM with EDX, UV–visible DRS and FT-RAMAN analysis. • Bi-doped ZnO nanocomposite material was used to photodegradation of Congo red. • Mechanism and photocatalytic effect of nanocomposite material have been discussed. - Abstract: Bismuth (Bi)-doped ZnO nanocomposite material was prepared by precipitation method with doping precursors of bismuthmore » nitrate pentahydrate and oxalic acid, characterized by X-ray diffraction (XRD), High Resolution-Scanning Electron Microscopy (HR-SEM) with Energy Dispersive X-ray (EDX) analysis, UV–visible Diffuse Reflectance Spectroscopy (UV–visible DRS) and Fourier Transform-Raman (FT-RAMAN) analysis. The enhanced photocatalytic activity of the Bi-doped ZnO is demonstrated through photodegradation of Congo red under UV-light irradiation. The mechanism of photocatalytic effect of Bi-doped ZnO nanocomposite material has been discussed.« less

ZnO:Gd nanocrystals for fluorescent applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Divya, N. K., E-mail: divyank90@gmail.com; Pradyumnan, P. P.

2016-05-23

Gadolinium doped ZnO crystals within the solubility limit of gadolinium in ZnO matrix were prepared by solid state reaction technique. The method is relatively less expense and enables the production in large scale. The samples were characterised by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), UV/Vis diffuse reflectance spectroscopy and photoluminescence techniques. Fluorescent property studies of gadolinium doped ZnO at room temperature show enhanced visible light emission due to the defects and oxygen vacancies produced via doping. This work reports the impact of gadolinium doping in the structural, optical and luminescent properties of ZnO inmore » detail.« less

Fabrication of a TiO2@porphyrin nanofiber hybrid material: a highly efficient photocatalyst under simulated sunlight irradiation

NASA Astrophysics Data System (ADS)

La, Duong Duc; Rananaware, Anushri; Phuong Nguyen Thi, Hoai; Jones, Lathe; Bhosale, Sheshanath V.

2017-03-01

The solar spectrum consists of 8% UV radiation, while 45% of solar energy is from visible light. It is therefore desirable to fabricate a hybrid material which is able to harvest energy from a wide range of photons from the sun for applications such as solar cells, photovoltaics, and photocatalysis. In this study we report on the fabrication of a TiO2@porphyrin hybrid material by surfactant-assisted co-assembly of monomeric porphyrin molecules with TiO2 nanoparticles. The obtained TiO2@porphyrin composite shows excellent integration of TiO2 particles with diameters of 15-30 nm into aggregated porphyrin nanofibers, which have a width of 70-90 nm and are several µm long. SEM, XPS, XRD, FTIR, UV-Vis and fluorescence spectroscopy were employed to characterize the TiO2@TCPP hybrid material. This material exhibits efficient photocatalytic performance under simulated sunlight, due to synergistic photocatalytic activities of the porphyrin aggregates in visible light and TiO2 particles in the UV region. A plausible mechanism for photocatalytic degradation is also proposed and discussed.

Characterization, Antibacterial and Antioxidant Properties of Silver Nanoparticles Synthesized from Aqueous Extracts of Allium sativum, Zingiber officinale, and Capsicum frutescens

PubMed Central

Otunola, Gloria Aderonke; Afolayan, Anthony Jide; Ajayi, Emmanuel Olusegun; Odeyemi, Samuel Wale

2017-01-01

Background: Herbal drug delivery is limited by poor solubility and bioavailability which can be overcome with suitable nanomaterials that will enhance their pharmacokinetics and performance. Objective: This study aimed to analyze the synthesis, characterization, and biological activities of silver nanoparticles (AgNPs) from three spices. Materials and Methods: AgNPs were prepared using 0.1 M silver nitrate and aqueous extracts of Allium sativum L. (garlic), Zingiber officinale Rosc. (ginger), and Capsicum frutescens L. (cayenne pepper). The AgNPs were characterized using ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Results: The AgNPs were formed within an hour of the reaction and showed maximum UV-Vis absorption in the 375–480 nm range. SEM and TEM revealed well-dispersed spherical particles with little agglomeration, average sizes of 3–6 nm, 3–22 nm, and 3–18 nm for garlic, ginger, and cayenne pepper, respectively. FTIR showed that amine, protein, phenolic, aromatic, and alkynes groups contributed to AgNP synthesis and XRD confirmed their crystalline and face-centered cubic nature. Antibacterial action of the AgNPs was in the following order: ginger (minimum inhibitory concentration [MIC] <25 μg/mL) > garlic> cayenne pepper (MIC 125 μg/mL). Antioxidant action showed cayenne pepper > ginger > garlic (inhibitory concentration 50% [IC50]: 40, 240, and 250 μg/mL, respectively) against 2,2-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) and garlic > cayenne pepper > ginger (IC50: <31.25, 40, and 120 μg/mL, respectively) against 1,1-diphenyl-2-picrylhydrazyl. Conclusion: Optimization of this green synthesis would support the production of AgNPs with great therapeutic potentials. SUMMARY The synthesis, characterization, and biological activities of silver nanoparticles (AgNPs) from garlic, ginger and cayenne pepper were evaluatedThe AgNPs formed were characterized using UV-Vis spectroscopy, SEM and TEM microscopy, as well as EDX, XRD and FTIR spectroscopy AgNPs were well dispersed with spherical shapes and average sizes of 3-6nm, 3-22nm and 3-18 nm for garlic, ginger and cayenne pepper respectivelyAmine, protein, phenolic and alkyne groups were revealed as the capping agents for the nanoparticlesThe silver nanoparticles were confirmed to be crystalline with characteristic face centred cubic natureThe antibacterial and antioxidant activities of the AgNPs confirmed the therapeutic potential of the AgNPs. Abbreviations used: AgNPs: Silver nanoparticles; UV-Vis: ultraviolet-visible; SEM: Scanning electron microscopy; TEM: Transmission electron microscopy; EDX: Energy dispersive X-ray; XRD: X-ray diffraction; FTIR: Fourier transform infrared; GaNPs: Garlic nanoparticles; GiNPs: Ginger nanoparticles; C.PeNPs: Cayenne pepper nanoparticles; FCC: Face centred cubic; SPR: Surface Plasmon resonance; ABTS-2: 2-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid); DPPH-1: 1-diphenyl-2-picrylhydrazyl. PMID:28808381

Characterization, Antibacterial and Antioxidant Properties of Silver Nanoparticles Synthesized from Aqueous Extracts of Allium sativum, Zingiber officinale, and Capsicum frutescens.

PubMed

Otunola, Gloria Aderonke; Afolayan, Anthony Jide; Ajayi, Emmanuel Olusegun; Odeyemi, Samuel Wale

2017-07-01

Herbal drug delivery is limited by poor solubility and bioavailability which can be overcome with suitable nanomaterials that will enhance their pharmacokinetics and performance. This study aimed to analyze the synthesis, characterization, and biological activities of silver nanoparticles (AgNPs) from three spices. AgNPs were prepared using 0.1 M silver nitrate and aqueous extracts of Allium sativum L. (garlic), Zingiber officinale Rosc. (ginger), and Capsicum frutescens L. (cayenne pepper). The AgNPs were characterized using ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. The AgNPs were formed within an hour of the reaction and showed maximum UV-Vis absorption in the 375-480 nm range. SEM and TEM revealed well-dispersed spherical particles with little agglomeration, average sizes of 3-6 nm, 3-22 nm, and 3-18 nm for garlic, ginger, and cayenne pepper, respectively. FTIR showed that amine, protein, phenolic, aromatic, and alkynes groups contributed to AgNP synthesis and XRD confirmed their crystalline and face-centered cubic nature. Antibacterial action of the AgNPs was in the following order: ginger (minimum inhibitory concentration [MIC] <25 μg/mL) > garlic> cayenne pepper (MIC 125 μg/mL). Antioxidant action showed cayenne pepper > ginger > garlic (inhibitory concentration 50% [IC50]: 40, 240, and 250 μg/mL, respectively) against 2,2-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) and garlic > cayenne pepper > ginger (IC50: <31.25, 40, and 120 μg/mL, respectively) against 1,1-diphenyl-2-picrylhydrazyl. Optimization of this green synthesis would support the production of AgNPs with great therapeutic potentials. The synthesis, characterization, and biological activities of silver nanoparticles (AgNPs) from garlic, ginger and cayenne pepper were evaluatedThe AgNPs formed were characterized using UV-Vis spectroscopy, SEM and TEM microscopy, as well as EDX, XRD and FTIR spectroscopy AgNPs were well dispersed with spherical shapes and average sizes of 3-6nm, 3-22nm and 3-18 nm for garlic, ginger and cayenne pepper respectivelyAmine, protein, phenolic and alkyne groups were revealed as the capping agents for the nanoparticlesThe silver nanoparticles were confirmed to be crystalline with characteristic face centred cubic natureThe antibacterial and antioxidant activities of the AgNPs confirmed the therapeutic potential of the AgNPs. Abbreviations used: AgNPs: Silver nanoparticles; UV-Vis: ultraviolet-visible; SEM: Scanning electron microscopy; TEM: Transmission electron microscopy; EDX: Energy dispersive X-ray; XRD: X-ray diffraction; FTIR: Fourier transform infrared; GaNPs: Garlic nanoparticles; GiNPs: Ginger nanoparticles; C.PeNPs: Cayenne pepper nanoparticles; FCC: Face centred cubic; SPR: Surface Plasmon resonance; ABTS-2: 2-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid); DPPH-1: 1-diphenyl-2-picrylhydrazyl.

Online UV-visible spectroscopy and multivariate curve resolution as powerful tool for model-free investigation of laccase-catalysed oxidation.

PubMed

Kandelbauer, A; Kessler, W; Kessler, R W

2008-03-01

The laccase-catalysed transformation of indigo carmine (IC) with and without a redox active mediator was studied using online UV-visible spectroscopy. Deconvolution of the mixture spectra obtained during the reaction was performed on a model-free basis using multivariate curve resolution (MCR). Thereby, the time courses of educts, products, and reaction intermediates involved in the transformation were reconstructed without prior mechanistic assumptions. Furthermore, the spectral signature of a reactive intermediate which could not have been detected by a classical hard-modelling approach was extracted from the chemometric analysis. The findings suggest that the combined use of UV-visible spectroscopy and MCR may lead to unexpectedly deep mechanistic evidence otherwise buried in the experimental data. Thus, although rather an unspecific method, UV-visible spectroscopy can prove useful in the monitoring of chemical reactions when combined with MCR. This offers a wide range of chemists a cheap and readily available, highly sensitive tool for chemical reaction online monitoring.

Glycation-assisted synthesized gold nanoparticles inhibit growth of bone cancer cells.

PubMed

Rahim, Moniba; Iram, Sana; Khan, Mohd Sajid; Khan, M Salman; Shukla, Ankur R; Srivastava, A K; Ahmad, Saheem

2014-05-01

This study presents a novel approach to synthesize glycogenic gold nanoparticles (glycogenic GNps) capped with glycated products (Schiff's base, Heyns products, fructosylamine etc.). These glycogenic GNps have been found to be active against human osteosarcoma cell line (Saos-2) with an IC50 of 0.187 mM, while the normal human embryonic lung cell line (L-132) remained unaffected up to 1mM concentration. The size of glycogenic GNps can also be controlled by varying the time of incubation of gold solution. Glycation reactions involving a combination of fructose and HSA (Human Serum Albumin) were found to be effective in the reduction of gold to glycogenic GNps whereas glucose in combination with HSA did not result in the reduction of gold. The progress of the reaction was followed using UV-visible spectroscopy and NBT (Nitroblue tetrazolium) assay. The glycogenic GNps were found to be spherical in shape with an average size of 24.3 nm, in a stable emulsion. These GNps were characterized using UV-visible spectroscopy, zeta potential analysis, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Copyright © 2013 Elsevier B.V. All rights reserved.

Structural, morphological and optical studies of F doped SnO2 thin films

NASA Astrophysics Data System (ADS)

Chandel, Tarun; Thakur, Vikas; Dwivedi, Shailendra Kumar; Zaman, M. Burhanuz; Rajaram, Poolla

2018-05-01

Highly conducting and transparent FTO (flourine doped tin Oxide) thin films were grown on the glass substrates using a low cost spray pyrolysis technique. The films were characterized for their structural, morphological and optical studies using XRD, SEM and UV-Vis spectroscopy. XRD studies show that the FTO films crystallize in Tetragonal cassiterite structure. Morphological analysis using SEM show that the films are uniformly covered with spherical grains albeit high in surface roughness. The average optical transmission greater than 80% in the visible region along with the appearance of interference fringes in the transmission curves confirms the high quality of the films. Electrical studies show that the films exhibit sheet resistance below 10 Ω ϒ-1.

Multifunctional Nanotherapeutic System for Advanced Prostate Cancer

DTIC Science & Technology

2012-10-01

aqueous part was again dialyzed against fresh deionized water two times for 12 hours. After dialysis the whole content was lyophilized using Freeze ... dryer (VirTis).The conjugate was characterized using UV visible spectroscopy, FT-IR spectroscopy and proton NMR. The results of the UV –Visible

A facile and green preparation of reduced graphene oxide using Eucalyptus leaf extract

NASA Astrophysics Data System (ADS)

Li, Chengyang; Zhuang, Zechao; Jin, Xiaoying; Chen, Zuliang

2017-11-01

In this paper, a green and facile synthesis of reduced graphene oxide (GO) by Eucalyptus leaf extract (EL-RGO) was investigated, which was characterized with ultraviolet-visible spectroscopy (UV), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and Thermal gravimetric analysis (TG). Eucalyptus leaf extract also play both reducing and capping stabilizing agents prepared EL-RGO as shown a good stability and electrochemical properties. This approach could provide an alternative method to prepare EL-RGO in large-scale production. Moreover, the good electrochemical property and biocompatibility can be used in various applications. In addition, the merit of this study is that both the oxidized products and the reducing agents are environmental friendly by green reduction.

Effect of catalyst concentration on size, morphology and optical properties of silica nanoparticles

NASA Astrophysics Data System (ADS)

Arora, Ekta; Ritu, Kumar, Sacheen; Kumar, Dinesh

2016-05-01

Today, nanomaterials play a key role in various fields such as electronics, aerospace, pharmaceuticals and biomedical because of their unique physical, chemical and biological properties which are different from bulk materials. Nano sized silica particles have gained the prominent position in scientific research and have wide applications. The sol-gel method is the best method to synthesize silica nanoparticles because of its potential to produce monodispersed with narrow size distribution at mild conditions. The silica nanoparticles were obtained by hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol act as solvent. The synthesized nanoparticles were characterized by Field Emission Scanning electron Microscope (FE-SEM), UV Spectrometer. The smallest size of silica particles is around 150nm examined by using FE-SEM. The optical properties and band structure was analyzed using UV-visible spectroscopy which is found to be increase by reducing the size of particles. Concentration effect of catalyst on the size, morphology and optical properties were analyzed.

Effect of catalyst concentration on size, morphology and optical properties of silica nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arora, Ekta; Ritu,; Kumar, Sacheen, E-mail: sacheen3@gmail.com

2016-05-06

Today, nanomaterials play a key role in various fields such as electronics, aerospace, pharmaceuticals and biomedical because of their unique physical, chemical and biological properties which are different from bulk materials. Nano sized silica particles have gained the prominent position in scientific research and have wide applications. The sol-gel method is the best method to synthesize silica nanoparticles because of its potential to produce monodispersed with narrow size distribution at mild conditions. The silica nanoparticles were obtained by hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol act as solvent. The synthesized nanoparticles were characterized by Field Emission Scanning electron Microscope (FE-SEM),more » UV Spectrometer. The smallest size of silica particles is around 150nm examined by using FE-SEM. The optical properties and band structure was analyzed using UV-visible spectroscopy which is found to be increase by reducing the size of particles. Concentration effect of catalyst on the size, morphology and optical properties were analyzed.« less

Metal-free inactivation of E. coli O157:H7 by fullerene/C3N4 hybrid under visible light irradiation.

PubMed

Ouyang, Kai; Dai, Ke; Chen, Hao; Huang, Qiaoyun; Gao, Chunhui; Cai, Peng

2017-02-01

Interest has grown in developing safe and high-performance photocatalysts based on metal-free materials for disinfection of bacterial pathogens under visible light irradiation. In this paper, the C 60 /C 3 N 4 and C 70 /C 3 N 4 hybrids were synthesized by a hydrothermal method, and characterized by X-ray diffraction (XRD), UV-vis diffuse reflection spectroscopy (UV-vis DRS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and high revolution transmission electron microscope (HRTEM). The performance of photocatalytic disinfection was investigated by the inactivation of Escherichia coli O157:H7. Both C 60 /C 3 N 4 and C 70 /C 3 N 4 hybrids showed similar crystalline structure and morphology with C 3 N 4 ; however, the two composites exhibited stronger bacterial inactivation than C 3 N 4 . In particular, C 70 /C 3 N 4 showed the highest bactericidal efficiency and was detrimental to all E. coli O157:H7 in 4h irradiation. Compared to C 3 N 4 , the enhancement of photocatalytic activity of composites could be attributed to the effective transfer of the photoinduced electrons under visible light irradiation. Owing to the excellent performance of fullerenes (C 60 , C 70 )/C 3 N 4 composites, a visible light response and environmental friendly photocatalysts for disinfection were achieved. Copyright © 2016. Published by Elsevier Inc.

Structure, morphology and optical properties of undoped and MN-doped ZnO(1-x)Sx nano-powders prepared by precipitation method

NASA Astrophysics Data System (ADS)

Dejene, F. B.; Onani, M. O.; Koao, L. F.; Wako, A. H.; Motloung, S. V.; Yihunie, M. T.

2016-01-01

The undoped and Mn-doped ZnO(1-x)Sx nano-powders were successfully synthesized by precipitation method without using any capping agent. Its structure, morphology, elemental analysis, optical and luminescence properties were determined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), UV-vis spectroscopy (UV) and photoluminescence spectroscopy (PL). A typical SEM image of the un-doped ZnO(1-x)Sx nanoparticles exhibit flake like structures that changes to nearly spherical particles with Mn-doping. The XRD of undoped and Mn doped ZnO(1-x)Sx pattern reveals the formation of a product indexed to the hexagonal wurtzite phase of ZnS. The nanopowders have crystallite sizes estimated from XRD measurements were in the range of 10-20 nm. All the samples showed absorption maximum of ZnO(1-x)Sx at 271 nm and high transmittance in UV and visible region, respectively. The undoped ZnO(1-x)Sx nanoparticles show strong room-temperature photoluminescence with four emission bands centering at 338 nm, 384 nm, 448 nm and 705 nm that may originate to the impurity of ZnO(1-x)Sx, existence of oxide related defects. The calculated bandgap of the nanocrystalline ZnO(1-x)Sx showed a blue-shift with respect to the Mn-doping. The PL spectra of the Mn-doped samples exhibit a strong orange emission at around 594 nm attributed to the 4T1-6A1 transition of the Mn2+ ions.

Optical and structural properties of carbon dots/TiO2 nanostructures prepared via DC arc discharge in liquid

NASA Astrophysics Data System (ADS)

Biazar, Nooshin; Poursalehi, Reza; Delavari, Hamid

2018-01-01

Synthesis and development of visible active catalysts is an important issue in photocatalytic applications of nanomaterials. TiO2 nanostructures coupled with carbon dots demonstrate a considerable photocatalytic activity in visible wavelengths. Extending optical absorption of a wide band gap semiconductor such as TiO2 with carbon dots is the origin of the visible activity of carbon dots modified semiconductor nanostructures. In addition, carbon dots exhibit high photostability, appropriate electron transport and chemical stability without considerable toxicity or environmental footprints. In this study, optical and structural properties of carbon dots/TiO2 nanostructures prepared via (direct current) DC arc discharge in liquid were investigated. Crystal structure, morphology and optical properties of the samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-visible spectroscopy respectively. SEM images show formation of spherical nanoparticles with an average size of 27 nm. In comparison with pristine TiO2, optical transmission spectrum of carbon dots/TiO2 nanostructures demonstrates an absorption edge at longer wavelengths as well a high optical absorption in visible wavelengths which is significant for visible activity of nanostructures as a photocatalyst. Finally, these results can provide a flexible and versatile pathway for synthesis of carbon dots/oxide semiconductor nanostructures with an appropriate activity under visible light.

Ultraviolet emission enhancement in ZnO thin films modified by nanocrystalline TiO2

NASA Astrophysics Data System (ADS)

Zheng, Gaige; Lu, Xi; Qian, Liming; Xian, Fenglin

2017-05-01

In this study, nanocrystalline TiO2 modified ZnO thin films were prepared by electron beam evaporation. The structural, morphological and optical properties of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV-visible spectroscopy, fluorescence spectroscopy, respectively. The composition of the films was examined by energy dispersive X-ray spectroscopy (EDX). The photoluminescent spectrum shows that the pure ZnO thin film exhibits an ultraviolet (UV) emission peak and a strong green emission band. Surface analysis indicates that the ZnO thin film contains many oxygen vacancy defects on the surface. After the ZnO thin film is modified by the nanocrystalline TiO2 layer, the UV emission of ZnO is largely enhanced and the green emission is greatly suppressed, which suggests that the surface defects such as oxygen vacancies are passivated by the TiO2 capping layer. As for the UV emission enhancement of the ZnO thin film, the optimized thickness of the TiO2 capping layer is ∼16 nm. When the thickness is larger than 16 nm, the UV emission of the ZnO thin film will decrease because the TiO2 capping layer absorbs most of the excitation energy. The UV emission enhancement in the nanocrystalline TiO2 modified ZnO thin film can be attributed to surface passivation and flat band effect.

Structure of Z-scheme CdS/CQDs/BiOCl heterojunction with enhanced photocatalytic activity for environmental pollutant elimination

NASA Astrophysics Data System (ADS)

Pan, Jinbo; Liu, Jianjun; Zuo, Shengli; Khan, Usman Ali; Yu, Yingchun; Li, Baoshan

2018-06-01

Z-scheme CdS/CQDs/BiOCl heterojunction was synthesized by a facile region-selective deposition process. Owing to the electronegativity of the groups on the surface of Carbon Quantum Dots (CQDs), they can be sandwiched between CdS and BiOCl, based on the stepwise region-selective deposition process. The samples were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), photoelectrochemical measurements and photoluminescence (PL). The results indicate that CQDs with size of 2-5 nm and CdS nanoparticles with size of 5-10 nm dispersed uniformly on the surface of cuboid BiOCl nanosheets. The photocatalytic performance tests reveal that the CdS/CQDs/BiOCl heterojunction exhibits much higher photocatalytic activity than that of BiOCl, CdS/BiOCl and CQDs/BiOCl for Rhodamine B (RhB) and phenol photodegradation under visible and UV light illumination, respectively. The enhanced photocatalytic performance should be attributed to the Z-scheme structure of CdS/CQDs/BiOCl, which not only improves visible light absorption and the migration efficiency of the photogenerated electron-holes but also keeps high redox ability of CdS/CQDs/BiOCl composite.

Preparation of TiO2/(TiO2-V2O5)/polypyrrole nanocomposites and a study on catalytic activities of the hybrid materials under UV/Visible light and in the dark

NASA Astrophysics Data System (ADS)

Piewnuan, C.; Wootthikanokkhan, J.; Ngaotrakanwiwat, P.; Meeyoo, V.; Chiarakorn, S.

2014-11-01

Hybrid metal oxides/polymer nanocomposites, namely TiO2/(TiO2-V2O5)/polypyrrole (PPy), were synthesized via in situ polymerization. Structures of the products were characterized by SEM-EDX, XRD, and FTIR techniques. The light absorbance and band gap energy values of the materials were evaluated by UV/Visible spectroscopy. The catalytic activity of the materials was determined from a degradation of methylene blue. It was found that, regardless of the polymerization time, the absorbance of TiO2/(TiO2-V2O5)/PPy was greater than those of TiO2/PPy and the neat TiO2, respectively. This was in accordance with the decrease in the band gap energy of the materials. The catalytic activity of TiO2/(TiO2-V2O5) was also observed in the dark. After polymerization, the catalytic activity of nanocomposite under UV/Visible light and in the dark was compromised. The above effects are discussed in the light of the energy storage ability of V2O5 and capability of the polymer in acting as a binder for the system.

Label-Free Ferrocene-Loaded Nanocarrier Engineering for In Vivo Cochlear Drug Delivery and Imaging.

PubMed

Youm, Ibrahima; Musazzi, Umberto M; Gratton, Michael Anne; Murowchick, James B; Youan, Bi-Botti C

2016-10-01

It is hypothesized that ferrocene (FC)-loaded nanocarriers (FC-NCs) are safe label-free contrast agents for cochlear biodistribution study by transmission electron microscopy (TEM). To test this hypothesis, after engineering, the poly(epsilon-caprolactone)/polyglycolide NCs are tested for stability with various types and ratios of sugar cryoprotectants during freeze-drying. Their physicochemical properties are characterized by UV-visible spectroscopy, dynamic light scattering, Fourier transform infrared spectroscopy, and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDS). The biodistribution of the FC-NCs in the cochlear tissue after intratympanic injection in guinea pigs is visualized by TEM. Auditory brainstem responses are measured before and after 4-day treatments. These FC-NCs have 153.4 ± 8.7 nm, 85.5 ± 11.2%, and -22.1 ± 1.1 mV as mean diameters, percent drug association efficiency, and zeta potential, respectively (n = 3). The incorporation of FC into the NCs is confirmed by Fourier transform infrared spectroscopy and SEM/EDS spectra. Lactose (3:1 ratio, v/v) is the most effective stabilizer after a 12-day study. The administered NCs are visible by TEM in the scala media cells of the cochlea. Based on auditory brainstem response data, FC-NCs do not adversely affect hearing. Considering the electrondense, radioactive, and magnetic properties of iron inside FC, FC-NCs are promising nanotemplate for future inner ear theranostics. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: A comparative study of photo catalysis on acid red 88

NASA Astrophysics Data System (ADS)

Balachandran, K.; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P.

2014-07-01

A novel, simple, less time-consuming and cost-effective wet chemical technique was used to synthesis TiO2 nanoparticles and TiO2-SiO2 nanocomposites using Titanium tetra isopropoxide (TTIP) as a precursor relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of TTIP and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6 h and dried at room temperature. The resulting powders were characterized by UV-Visible spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM). The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy-energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy. Surface area of the composite as calculated by BET analyzer and it was found to be 65 and 75 m2/g for TiO2 and TiO2-SiO2 respectively. The photocatalytic experiments were performed with aqueous solution of acid red 88 with TiO2 and TiO2-SiO2 batch studies for 4 h irradiation, direct photolysis of TiO2 and TiO2-SiO2 contributed 94.2% and 96.5% decomposition in solar radiation for the optimized concentration of acid red 88.

Engineered 3D-scaffolds of photocrosslinked chitosan-gelatin hydrogel hybrids for chronic wound dressings and regeneration.

PubMed

Carvalho, Isadora C; Mansur, Herman S

2017-09-01

Wound repair is one of the most complex biological processes in human life. To date, no ideal biomaterial solution has been identified, which that encompasses all functions and properties of real skin tissue. Thus, this study focused on the synthesis of new biocompatible hybrid hydrogel scaffolds based on methacrylate-functionalized high molecular mass chitosan with gelatin-A photocrosslinked with UV radiation to tailor matrix network properties. These hybrid hydrogels were produced via freeze-drying and were extensively characterized by swelling and degradation measurements, Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy (UV-Vis), scanning electron microscopy (SEM-EDS), and micro-computed tomography (micro-CT). The results demonstrated that hydrogels were produced with broadly designed swelling degrees typically ranging from 500% to 2000%, which were significantly dependent on the relative concentration of polymers and irradiation time for crosslinking. Analogously, degradation was reduced with increased photocrosslinking of the network. Moreover, insights into the mechanism of photochemical crosslinking were suggested based on FTIR and UV-Vis analyses of the characteristic functional groups involved in the reactions. SEM analysis associated with micro-CT imaging of the hybrid scaffolds showed uniformly interconnected 3D porous structures, with architectural features affected by the crosslinking of the network. These hydrogels were biocompatible, with live cell viability responses of human embryonic kidney (HEK293T) cells being above 95%. Hence, novel hybrid hydrogels were designed and produced with tunable properties through photocrosslinking and with a biocompatible response suitable for use in wound dressing and skin tissue repair applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Shape- and Size-Controlled Synthesis of Silver Nanoparticles Using Aloe vera Plant Extract and Their Antimicrobial Activity

NASA Astrophysics Data System (ADS)

Logaranjan, Kaliyaperumal; Raiza, Anasdass Jaculin; Gopinath, Subash C. B.; Chen, Yeng; Pandian, Kannaiyan

2016-11-01

Biogenic synthesis of silver nanoparticles (AgNP) was performed at room temperature using Aloe vera plant extract in the presence of ammoniacal silver nitrate as a metal salt precursor. The formation of AgNP was monitored by UV-visible spectroscopy at different time intervals. The shape and size of the synthesized particle were visualized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. These results were confirmed by X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses and further supported by surface-enhanced Raman spectroscopy/Raman scattering (SERS) study. UV-visible spectrum has shown a sharp peak at 420 nm and further evidenced by FTIR peak profile (at 1587.6, 1386.4, and 1076 cm-1 with corresponding compounds). The main band position with SERS was noticed at 1594 cm-1 (C-C stretching vibration). When samples were heated under microwave radiation, AgNP with octahedron shapes with 5-50 nm were found and this method can be one of the easier ways to synthesis anisotropic AgNP, in which the plant extract plays a vital role to regulate the size and shape of the nanoparticles. Enhanced antibacterial effects (two- to fourfold) were observed in the case of Aloe vera plant protected AgNP than the routinely synthesized antibiotic drugs.

One-Pot Route towards Active TiO2 Doped Hierarchically Porous Cellulose: Highly Efficient Photocatalysts for Methylene Blue Degradation

PubMed Central

Sun, Xiaoxia; Wang, Kunpeng; Shu, Yu; Zou, Fangdong; Zhang, Boxing; Sun, Guangwu; Uyama, Hiroshi; Wang, Xinhou

2017-01-01

In this study, novel photocatalyst monolith materials were successfully fabricated by a non-solvent induced phase separation (NIPS) technique. By adding a certain amount of ethyl acetate (as non-solvent) into a cellulose/LiCl/N,N-dimethylacetamide (DMAc) solution, and successively adding titanium dioxide (TiO2) nanoparticles (NPs), cellulose/TiO2 composite monoliths with hierarchically porous structures were easily formed. The obtained composite monoliths possessed mesopores, and two kinds of macropores. Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Brunauer-Emmett-Teller (BET), and Ultraviolet-visible Spectroscopy (UV-Vis) measurements were adopted to characterize the cellulose/TiO2 composite monolith. The cellulose/TiO2 composite monoliths showed high efficiency of photocatalytic activity in the decomposition of methylene blue dye, which was decomposed up to 99% within 60 min under UV light. Moreover, the composite monoliths could retain 90% of the photodegradation efficiency after 10 cycles. The novel NIPS technique has great potential for fabricating recyclable photocatalysts with highly efficiency. PMID:28772734

One Step Synthesis of NiO Nanoparticles via Solid-State Thermal Decomposition at Low-Temperature of Novel Aqua(2,9-dimethyl-1,10-phenanthroline)NiCl2 Complex

PubMed Central

Barakat, Assem; Al-Noaimi, Mousa; Suleiman, Mohammed; Aldwayyan, Abdullah S.; Hammouti, Belkheir; Ben Hadda, Taibi; Haddad, Salim F.; Boshaala, Ahmed; Warad, Ismail

2013-01-01

[NiCl2(C14H12N2)(H2O)] complex has been synthesized from nickel chloride hexahydrate (NiCl2·6H2O) and 2,9-dimethyl-1,10-phenanthroline (dmphen) as N,N-bidentate ligand. The synthesized complex was characterized by elemental analysis, infrared (IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy and differential thermal/thermogravimetric analysis (TG/DTA). The complex was further confirmed by single crystal X-ray diffraction (XRD) as triclinic with space group P-1. The desired complex, subjected to thermal decomposition at low temperature of 400 ºC in an open atmosphere, revealed a novel and facile synthesis of pure NiO nanoparticles with uniform spherical particle; the structure of the NiO nanoparticles product was elucidated on the basis of Fourier transform infrared (FT-IR), UV-vis spectroscopy, TG/DTA, XRD, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDXS) and transmission electron microscopy (TEM). PMID:24351867

UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi

PubMed Central

Lando, Gabriela Albara; Marconatto, Letícia; Schrank, Augusto; Vainstein, Marilene Henning

2017-01-01

Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU) are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae, when the films were pre-treated with Ultraviolet (UV) irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR), scanning electron microscopy (SEM), and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management. PMID:28718785

Nb2O5 nanowires in-situ grown on carbon fiber: A high-efficiency material for the photocatalytic reduction of Cr(VI).

PubMed

Du, Yucheng; Zhang, Shihao; Wang, Jinshu; Wu, Junshu; Dai, Hongxing

2018-04-01

Niobium oxide nanowire-deposited carbon fiber (CF) samples were prepared using a hydrothermal method with amorphous Nb 2 O 5 ·nH 2 O as precursor. The physical properties of the samples were characterized by means of numerous techniques, including X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), UV-visible spectroscopy (UV-vis), N 2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy. The efficiency for the removal of Cr(VI) was determined. Parameters such as pH value and initial Cr(VI) concentration could influence the Cr(VI) removal efficiency or adsorption capacity of the Nb 2 O 5 /carbon fiber sample obtained after hydrothermal treatment at 160°C for 14hr. The maximal Cr(VI) adsorption capacity of the Nb 2 O 5 nanowire/CF sample was 115mg/g. This Nb 2 O 5 /CF sample also showed excellent photocatalytic activity and stability for the reduction of Cr(VI) under UV-light irradiation: the Cr(VI) removal efficiency reached 99.9% after UV-light irradiation for 1hr and there was no significant decrease in photocatalytic performance after the use of the sample for 10 repeated cycles. Such excellent Cr(VI) adsorption capacity and photocatalytic performance was related to its high surface area, abundant surface hydroxyl groups, and good UV-light absorption ability. Copyright © 2017. Published by Elsevier B.V.

Preparation of Pd/Fe3O4 nanoparticles by use of Euphorbia stracheyi Boiss root extract: A magnetically recoverable catalyst for one-pot reductive amination of aldehydes at room temperature.

PubMed

Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad

2016-02-15

We describe a method for supporting palladium nanoparticles on magnetic nanoparticles using Euphorbia stracheyi Boiss root extract as the natural source of reducing and stabilizing agent. The progress of the reaction was monitored using UV-visible spectroscopy. The nanocatalyst was characterized by FE-SEM, TEM, XRD, EDS, FT-IR spectroscopy and ICP. The nanocatalyst was applied as an efficient, magnetically recoverable, highly reusable and heterogeneous catalyst for one-pot reductive amination of aldehydes at room temperature. The nanocatalyst was easily recovered by applying an external magnet and reused several times without considerable loss of activity. Copyright © 2015 Elsevier Inc. All rights reserved.

Neoteric environmental detoxification of organic pollutants and pathogenic microbes via green synthesized ZnO nanoparticles.

PubMed

Jaffri, Shaan Bibi; Ahmad, Khuram Shahzad

2018-06-13

Present study has for the first time reported Prunus cerasifera leaf extract mediated zinc oxide nanoparticles in a green and one pot synthetic mode without utilization of any chemical reducing agents. Synthesized nanoparticles were analyzed by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), fourier transmission infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). UV-Vis peak was detected at 380 nm due to surface plasmon resonance (SPR). Variety of biomolecules were revealed by FTIR involved in reduction cum stabilization of zinc oxide nanoparticles. Wurtzite hexagonal geometry with an average crystallite size of 12 nm was obtained from XRD diffraction pattern. SEM exhibited size ranges of 80-100 nm and 60- 100 nm for 200 ℃ and 600 ℃ calcination temperatures. Synthesized nanoparticles were used as bio-cleaning photocatalysts against organic pollutants i.e. bromocresol green, bromophenol blue, methyl red and methyl blue, which yielded pseudo first order reaction kinetics (R 2 = 0.98, 0.92, 0.92, 0.90 respectively). Pollutants expressed higher degradation percentages in less than 14 min in direct solar irradiance. Moreover, synthesized nanoparticles were tested against resistant microbes i.e. Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Aspergillus terreus, Penicillium chrysogenum, Fusarium solani, Lasiodiplodia theobromae, Xanthomonas axonopodis pv. citri and Psuedomonas syringae for development of new generation of antimicrobial agents.

Passive optical limiting studies of nanostructured Cu doped ZnO-PVA composite thin films

NASA Astrophysics Data System (ADS)

Tamgadge, Y. S.; Sunatkari, A. L.; Talwatkar, S. S.; Pahurkar, V. G.; Muley, G. G.

2016-01-01

We prepared undoped and Cu doped ZnO semiconducting nanoparticles (NPs) by chemical co-precipitation method and obtained Cu doped ZnO-polyvinyl alcohol (PVA) nanocomposite thin films by spin coating to investigate third order nonlinear optical and optical limiting properties under cw laser excitation. Powder samples of NPs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy, transmission electron microscopy, ultraviolet-visible (UV-vis) and Fourier transform infrared spectroscopy. XRD pattern and FE-SEM micrograph revealed the presence of hexagonal wurtzite phase ZnO NPs having uniform morphology with average particle size of 20 nm. The presence of excitons and absorption peaks in the range 343-360 nm, revealed by UV-vis study, were attributed to excitons in n = 1 quantum state. Third order NLO properties of all composite thin films were investigated by He-Ne continuous wave (cw) laser of wavelength 632.8 nm using Z-scan technique. Thermally stimulated enhanced values of nonlinear refraction and absorption coefficients were obtained which may be attributed to self-defocusing effect, reverse saturable absorption, weak free carrier absorption and surface states properties originated from thermo optic effect. Optical limiting properties have been studied using cw diode laser of wavelength 808 nm and results are presented.

Synthesis and characterization of high-quality cobalt vanadate crystals and their applications in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Bhuiyan, Md. Tofajjol Hossen; Rahman, Md. Afjalur; Rahman, Md. Atikur; Sultana, Rajia; Mostafa, Md. Rakib; Tania, Asmaul Husna; Sarker, Md. Abdur Razzaque

2016-12-01

High-quality cobalt vanadate crystals have been synthesized by solid-state reaction route. Structure and morphology of the synthesized powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectroscopy. The XRD patterns revealed that the as prepared materials are of high crystallinity and high quality. The SEM images showed that the crystalline CoV2O6 material is very uniform and well separated, with particle (of) area 252 μm. The electronic and optical properties were investigated by impedance analyzer and UV-visible spectrophotometer. Temperature-dependent electrical resistivity was measured using four-probe technique. The crystalline CoV2O6 material is a semiconductor and its activation energy is 0.05 eV.

Enhancement of visible-light photoactivity by polypropylene coated plasmonic Au/TiO2 for dye degradation in water solution

NASA Astrophysics Data System (ADS)

D'Amato, C. A.; Giovannetti, R.; Zannotti, M.; Rommozzi, E.; Ferraro, S.; Seghetti, C.; Minicucci, M.; Gunnella, R.; Di Cicco, A.

2018-05-01

A new approach to obtain a heterogeneous photocatalytic material with gold nanoparticles and TiO2 semiconductor was performed exploiting the reducing ability of acetylacetone, a chemical present in the TiO2 paste formulation. Gold/TiO2 heterogeneous catalyst supported on polypropylene [PP@Au-TiO2]A was prepared; composition, structure and morphology of this new material were defined by using UV-Vis spectroscopy, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray diffraction (XRD), X-ray Fluorescence (XRF), Raman Spectroscopy, Photoluminescence and Diffuse Reflectance Spectroscopy. The new material was tested in the photocatalytic degradation of Alizarin Red S in water solution, as target pollutant, under visible light and correlated with structural and spectroscopic characterizations. [PP@Au-TiO2]A showed higher photocatalytic activity respect to pure [PP@TiO2]A with an improvement of photodegradation kinetic. The best performance was obtained using [PP@Au-TiO2]A sample with 0.006 wt.% of Au and the photocatalytic improvement was correlated with the band gap energy decrease of photocatalyst.

Investigation on Structural and Optical Properties of Copper Telluride Thin Films with Different Annealing Temperature

NASA Astrophysics Data System (ADS)

Nishanthini, R.; Muthu Menaka, M.; Pandi, P.; Bahavan Palani, P.; Neyvasagam, K.

The copper telluride (Cu2Te) thin film of thickness 240nm was coated on a microscopic glass substrate by thermal evaporation technique. The prepared films were annealed at 150∘C and 250∘C for 1h. The annealing effect on Cu2Te thin films was examined with different characterization methods like X-ray Diffraction Spectroscopy (XRD), Scanning Electron Microscopy (SEM), Ultra Violet-Visible Spectroscopy (UV-VIS) and Photoluminescence (PL) Spectroscopy. The peak intensities of XRD spectra were increased while increasing annealing temperature from 150∘C to 250∘C. The improved crystallinity of the thin films was revealed. However, the prepared films are exposed complex structure with better compatibility. Moreover, the shift in band gap energy towards higher energies (blue shift) with increasing annealing temperature is observed from the optical studies.

Synthesis, physicochemical and optical properties of bis-thiosemicarbazone functionalized graphene oxide

NASA Astrophysics Data System (ADS)

Kumar, Santosh; Wani, Mohmmad Y.; Arranja, Claudia T.; Castro, Ricardo A. E.; Paixão, José A.; Sobral, Abilio J. F. N.

2018-01-01

Fluorescent materials are important for low-cost opto-electronic and biomedical sensor devices. In this study we present the synthesis and characterization of graphene modified with bis-thiosemicarbazone (BTS). This new material was characterized using Fourier transform infrared spectroscopy (FT-IR), Ultraviolet-visible (UV-Vis) and Raman spectroscopy techniques. Further evaluation by X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and atomic-force microscopy (AFM) allowed us to fully characterize the morphology of the fabricated material. The average height of the BTSGO sheet is around 10 nm. Optical properties of BTSGO evaluated by photoluminescence (PL) spectroscopy showed red shift at different excitation wavelength compared to graphene oxide or bisthiosemicarbazide alone. These results strongly suggest that BTSGO material could find potential applications in graphene based optoelectronic devices.

The extraction of gold nanoparticles from oat and wheat biomasses using sodium citrate and cetyltrimethylammonium bromide, studied by x-ray absorption spectroscopy, high-resolution transmission electron microscopy, and UV-visible spectroscopy.

PubMed

Armendariz, Veronica; Parsons, Jason G; Lopez, Martha L; Peralta-Videa, Jose R; Jose-Yacaman, Miguel; Gardea-Torresdey, Jorge L

2009-03-11

Gold (Au) nanoparticles can be produced through the interaction of Au(III) ions with oat and wheat biomasses. This paper describes a procedure to recover gold nanoparticles from oat and wheat biomasses using cetyltrimethylammonium bromide or sodium citrate. Extracts were analyzed using UV-visible spectroscopy, high-resolution transmission electron microscopy (HRTEM), and x-ray absorption spectroscopy. The HRTEM data demonstrated that smaller nanoparticles are extracted first, followed by larger nanoparticles. In the fourth extraction, coating of chelating agents is visible on the extracted nanoparticles.

Pyrogallol-imprinted polymers with methyl methacrylate via precipitation polymerization

NASA Astrophysics Data System (ADS)

Mehamod, Faizatul Shimal; Othman, Nor Amira; Bulat, Ku Halim Ku; Suah, Faiz Bukhari Mohd

2018-06-01

Molecular simulation techniques are important to study the understanding of chemical and physical properties of any material. Computational modeling is considered as time reducer in finding the best recipes for Molecularly-Imprinted Polymers (MIPs). In this study, Pyrogallol-imprinted polymers (PIP) and non-imprinted polymers (NIPs) were synthesized via precipitation polymerization using Pyrogallol (Py), methyl methacrylate (MMA), divinylbenzene (DVB) as template, functional monomer and cross-linker, respectively. The recipe was according to the results from computational techniques. The synthesized PIP and NIPs were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) and UV-visible spectroscopy (UV-vis). Studies on adsorption isotherm showed that PIP and NIPs follow Scatchard isotherm models. Sorption kinetic study found that PIP and NIPs follow pseudo-second order which indicates the rate-limiting step is the surface adsorption. The imprinting factor of PIP was determined by selectivity study and showed the value of k >1, which proved that PIP was selective toward Pyrogallol compared to NIP.

Synthesis and photocatalytic activity of anatase TiO2 nanoparticles for degradation of methyl orange

NASA Astrophysics Data System (ADS)

Singh, Manmeet; Duklan, Neha; Singh, Pritpal; Sharma, Jeewan

2018-05-01

In present study, TiO2 nanoparticles, in anatase form, were successfully synthesized using TiCl4 as precursor. These nanoparticles were synthesized by sol-gel method at room temperature (298 K). As prepared samples were characterized for phase structure, optical absorption and surface properties using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Raman spectroscopy and UV-Visible spectroscopy. The synthesized TiO2 nanoparticles sample was compared with one of the most efficient commercial photocatalyst Degussa TiO2 also known as P(25). The effect of phase composition of anatase TiO2 nanoparticles, as compared to P(25), on photocatalytic decomposition of organic dye, methyl orange (MO) was studies under UV light illumination. An enhanced degradation of hazardous dye was observed in the presence of anatase TiO2 nanoparticles as compared to P(25) due to slow recombination rate. Other possible reasons for this enhancement have also been discussed.

UV shielding with visible transparency based properties of poly (styrene-co-acrylonitrile)/Ag doped ZnO nanocomposite

NASA Astrophysics Data System (ADS)

Singh, Rajender; Verma, Karan; Singh, Tejbir; Barman, P. B.; Sharma, Dheeraj

2018-02-01

Development of ultraviolet (UV) shielding with visible transparency based thermoplastic polymer nanocomposite (PNs) presents an important requisite in terms of their efficiency and cost. Present study contributed for the same approach by dispersion of Ag doped ZnO nanoparticles upto 10 wt% in poly (styrene-co-acrylonitrile) matrix by insitu emulsion polymerization method. The crystal and chemical structure of PNs has been analyzed by x-ray diffraction (XRD) and fourier infrared spectrometer (FTIR) techniques. The morphological and elemental information of synthesized nanomaterial has been studied by field emission scanning electron microscope (FESEM) and energy dispersive spectroscopy (EDS) technique. The optical properties of PNs has been studied by UV-visible spectroscopy technique. The incorporation of nanoparticles in polymer matrix absorb the complete UV light with visible transparency. The present reported polymer nanocomposite (PNs) have tuned refractive index with UV blocking and visible transparency based properties which can serve as a viable alternative as compared to related conventional materials.

The photocatalytic investigation of methylene blue dye with Cr doped zinc oxide nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ray, Rajeev; Kumar, Ashavani, E-mail: ashavani@yahoo.com

2015-08-28

The present work reports eco-friendly and cost effective sol-gel technique for synthesis of Chromium doped ZnO nanoparticles at room temperature. In this process Zinc nitrate, Chromium nitrate were used as precursor. Structural as well as optical properties of Cr induced ZnO samples were analysed by X-ray diffraction technique (XRD), SEM, PL and UV-Visible spectroscopy (UV-Vis) respectively. XRD analysis shows that the samples have hexagonal (wurtzite) structure with no additional peak which suggests that Cr ions fit into the regular Zn sites of ZnO crystal structure. By using Scherrer’s formula for pure and Cr doped ZnO samples the average grain sizemore » was found to be 32 nm. Further band gap of pure and doped ZnO samples have been calculated by using UV-Vis spectra. The photo-catalytic degradation of methyl blue dye under UV irradiation was examined for synthesized samples. The results show that the concentration plays an important role in photo-catalytic activity.« less

Synthesis of silica coated zinc oxide–poly(ethylene-co-acrylic acid) matrix and its UV shielding evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramasamy, Mohankandhasamy; Kim, Yu Jun; Gao, Haiyan

Graphical abstract: - Highlights: • Well layer thickness controlled silica shell was made on ZnO nanoparticles. • PEAA, an interfacial agent is used to make nanocomposite–polymer matrix by twin-screw extruder. • Si-ZnO/PEAA matrix is highly stable and UV protective as compared to ZnO/PEAA matrix. • Nanoparticle embedded polymer matrix is suggested to make UV shielding fabrics with Nylon4. - Abstract: Silica coated zinc oxide nanoparticles (Si-ZnO NPs) (7 nm thick) were synthesized successfully and melt blended with poly(ethylene-co-acrylic acid) (PEAA resin) to improving ultraviolet (UV) shielding of zinc oxide nanoparticles (ZnO NPs). The photostability of both the ZnO NPs andmore » Si-ZnO NPs were analyzed by the difference in photoluminescence (PL) and by methylene blue (MB) degradation. Photo-degradation studies confirmed that Si-ZnO NPs are highly photostable compared to ZnO NPs. The melt blended matrices were characterized by field emission scanning electron microscopy interfaced with energy dispersive X-ray spectroscopy (FE-SEM-EDX). The UV shielding property was analyzed from the transmittance spectra of UV–visible (UV–vis) spectroscopy. The results confirmed fine dispersion of thick Si-ZnO NPs in the entire resin matrix. Moreover, the Si-ZnO/PEAA showed about 97% UV shielding properties than the ZnO/PEAA.« less

Novel synthesis and structural analysis of zinc oxide nanoparticles for the non enzymatic glucose biosensor.

PubMed

Dayakar, T; Venkateswara Rao, K; Bikshalu, K; Rajendar, V; Park, Si-Hyun

2017-06-01

A non-enzymatic glucose biosensor was developed by utilizing the zinc oxide nanoparticles (ZnO NPs) synthesized by a novel green method using the leaf extract of Ocimum tenuiflorum. The structural, optical and morphological properties of ZnO NPs characterized by means of X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDAX) spectroscopy, and transmission electron microscopy (TEM). The XRD analysis revealed that the ZnO NPs were crystalline and had a hexagonal wurtzite structure. The crystallite size measured by XRD was the same as that measured using SEM and TEM. The UV-vis absorption spectrum estimates the band gap of ZnO NPs present in the range of 2.82 to 3.45eV. The reduction and formation of ZnO NPs mainly due to the involvement of leaf extract bio-molecular compounds analyzed from the FTIR spectra. The SEM result confirms the morphology of the NPs responsible from the various concentration of leaf extract in the synthesis process. HRTEM analysis depicts the spherical structure of ZnO NPs. The synthesized NPs have the average size ranges from 10 to 20nm. The fabricated GCE/ZnO glucose sensor represents superior electro catalytic activity that has been observed for ZnO NPs with a reproducible sensitivity of 631.30μAmM -1 cm -2 , correlation coefficient of R=0.998, linear dynamic range from 1-8.6mM, low detection limit of 0.043μM (S/N=3) and response time<4s. Copyright © 2017 Elsevier B.V. All rights reserved.

Efficient visible-light photocatalytic degradation of sulfadiazine sodium with hierarchical Bi₇O₉I₃under solar irradiation.

PubMed

Xu, MengMeng; Zhao, YaLei; Yan, QiShe

2015-01-01

Bi₇O₉I₃, a kind of visible-light-responsive photocatalyst, with hierarchical micro/nano-architecture was successfully synthesized by oil-bath heating method, with ethylene glycol as solvent, and applied to degrade sulfonamide antibiotics. The as-prepared product was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflection spectra and scanning electron microscopy (SEM). XRD and XPS tests confirmed that the product was indeed Bi₇O₉I₃. The result of SEM observation shows that the as-synthesized Bi₇O₉I₃ consists of a large number of micro-sheets with parallel rectangle structure. The optical test exhibited strong photoabsorption in visible light irradiation, with 617 nm of absorption edges. Moreover, the difference in the photocatalytic efficiency of as-prepared Bi₇O₉I₃ at different seasons of a whole year was investigated in this study. The chemical oxygen demand removal efficiency and concentration of NO(3)(-) and SO(4)(2-) of solution after reaction were also researched to confirm whether degradation of the pollutant was complete; the results indicated a high mineralization capacity of Bi₇O₉I₃. The as-synthesized Bi₇O₉I₃exhibits an excellent oxidizing capacity of sulfadiazine sodium and favorable stability during the photocatalytic reaction.

High photocatalytic activity of hierarchical SiO2@C-doped TiO2 hollow spheres in UV and visible light towards degradation of rhodamine B.

PubMed

Zhang, Ying; Chen, Juanrong; Hua, Li; Li, Songjun; Zhang, Xuanxuan; Sheng, Weichen; Cao, Shunsheng

2017-10-15

Ongoing research activities are targeted to explore high photocatalytic activity of TiO 2 -based photocatalysts for the degradation of environmental contaminants under UV and visible light irradiation. In this work, we devise a facile, cost-effective technique to in situ synthesize hierarchical SiO 2 @C-doped TiO 2 (SCT) hollow spheres for the first time. This strategy mainly contains the preparation of monodisperse cationic polystyrene spheres (CPS), sequential deposition of inner SiO 2 , the preparation of the sandwich-like CPS@SiO 2 @CPS particles, and formation of outer TiO 2 . After the one-step removal of CPS templates by calcination at 450°C, hierarchical SiO 2 @C-doped TiO 2 hollow spheres are in situ prepared. The morphology, hierarchical structure, and properties of SCT photocatalyst were characterized by TEM. SEM, STEM Mapping, BET, XRD, UV-vis spectroscopy, and XPS. Results strongly confirm the carbon doping in the outer TiO 2 lattice of SCT hollow spheres. When the as-synthesized SCT hollow spheres were employed as a photocatalyst for the degradation of Rhodamine B under visible-light and ultraviolet irradiation, the SCT photocatalyst exhibits a higher photocatalytic activity than commercial P25, effectively overcoming the limitations of poorer UV activity for many previous reported TiO 2 -based photocatalysts due to doping. Copyright © 2017 Elsevier B.V. All rights reserved.

In Situ UV-Visible Assessment of Iron-Based High-Temperature Water-Gas Shift Catalysts Promoted with Lanthana: An Extent of Reduction Study

DOE PAGES

Hallac, Basseem B.; Brown, Jared C.; Stavitski, Eli; ...

2018-02-04

Here, the extent of reduction of unsupported iron-based high-temperature water-gas shift catalysts with small (<5 wt %) lanthana contents was studied using UV-visible spectroscopy. Temperature- programmed reduction measurements showed that lanthana content higher than 0.5 wt % increased the extent of reduction to metallic Fe, while 0.5 wt % of lanthana facilitated the reduction to Fe 3O 4. In situ measurements on the iron oxide catalysts using mass and UV-visible spectroscopies permitted the quantification of the extent of reduction under temperature-programmed reduction and high-temperature water-gas shift conditions. The oxidation states were successfully calibrated against normalized absorbance spectra of visible lightmore » using the Kubelka-Munk theory. The normalized absorbance relative to the fully oxidized Fe 2O 3 increased as the extent of reduction increased. XANES suggested that the average bulk iron oxidation state during the water-gas shift reaction was Fe +2.57 for the catalyst with no lanthana and Fe +2.54 for the catalysts with 1 wt % lanthana. However, the UV-vis spectra suggest that the surface oxidation state of iron would be Fe +2.31 for the catalyst with 1 wt % lanthana if the oxidation state of iron in the catalyst with 0 wt % lanthana were Fe +2.57. The findings of this paper emphasize the importance of surface sensitive UV-visible spectroscopy for determining the extent of catalyst reduction during operation. Furthermore, the paper highlights the potential to use bench-scale UV-visible spectroscopy to study the surface chemistry of catalysts instead of less-available synchrotron X-ray radiation facilities.« less

In Situ UV-Visible Assessment of Iron-Based High-Temperature Water-Gas Shift Catalysts Promoted with Lanthana: An Extent of Reduction Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hallac, Basseem B.; Brown, Jared C.; Stavitski, Eli

Here, the extent of reduction of unsupported iron-based high-temperature water-gas shift catalysts with small (<5 wt %) lanthana contents was studied using UV-visible spectroscopy. Temperature- programmed reduction measurements showed that lanthana content higher than 0.5 wt % increased the extent of reduction to metallic Fe, while 0.5 wt % of lanthana facilitated the reduction to Fe 3O 4. In situ measurements on the iron oxide catalysts using mass and UV-visible spectroscopies permitted the quantification of the extent of reduction under temperature-programmed reduction and high-temperature water-gas shift conditions. The oxidation states were successfully calibrated against normalized absorbance spectra of visible lightmore » using the Kubelka-Munk theory. The normalized absorbance relative to the fully oxidized Fe 2O 3 increased as the extent of reduction increased. XANES suggested that the average bulk iron oxidation state during the water-gas shift reaction was Fe +2.57 for the catalyst with no lanthana and Fe +2.54 for the catalysts with 1 wt % lanthana. However, the UV-vis spectra suggest that the surface oxidation state of iron would be Fe +2.31 for the catalyst with 1 wt % lanthana if the oxidation state of iron in the catalyst with 0 wt % lanthana were Fe +2.57. The findings of this paper emphasize the importance of surface sensitive UV-visible spectroscopy for determining the extent of catalyst reduction during operation. Furthermore, the paper highlights the potential to use bench-scale UV-visible spectroscopy to study the surface chemistry of catalysts instead of less-available synchrotron X-ray radiation facilities.« less

The chitosan - Porphyrazine hybrid materials and their photochemical properties.

PubMed

Chełminiak-Dudkiewicz, Dorota; Ziegler-Borowska, Marta; Stolarska, Magdalena; Sobotta, Lukasz; Falkowski, Michal; Mielcarek, Jadwiga; Goslinski, Tomasz; Kowalonek, Jolanta; Węgrzynowska-Drzymalska, Katarzyna; Kaczmarek, Halina

2018-04-01

Three magnesium sulfanyl porphyrazines differing in the size of peripheral substituents (3,5-dimethoxybenzylsulfanyl, (3,5-dimethoxybenzyloxy)benzylsulfanyl, 3,5-bis[(3,5-bis[(3,5-dimethoxybenzyloxy)benzyloxy]benzylsulfanyl) were exposed to visible and ultraviolet radiation (UV A + B + C) in order to determine their photochemical properties. The course of photochemical reactions in dimethylformamide solutions and the ability of the systems to generate singlet oxygen were studied by UV-Vis spectroscopy, which additionally gave information on aggregation processes. The porphyrazines were found to be stable upon visible light irradiation conditions, but when exposed to high energy UV radiation, the efficient photodegradation of these macrocycles was observed. Therefore, these three magnesium sulfanyl porphyrazines were incorporated into chitosan matrix. The obtained thin films of chitosan doped with porphyrazines were subjected to polychromatic UV-radiation and studied by spectroscopic methods (UV-Vis, FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Application of chitosan as a polymer matrix for porphyrazines was found to be successful method that effectively stopped the unwelcome degradation of macrocycles, thus worth considering for their photoprotection. In addition, the surface properties of the hybrid material were determined by contact angle measurements and calculation of surface free energy. Intermolecular interactions between these novel porphyrazines and chitosan were detected. The mechanism of photochemical reactions occurring in studied systems has been discussed. Copyright © 2018 Elsevier B.V. All rights reserved.

Facile fabrication of CuO-Pb2O3 nanophotocatalyst for efficient degradation of Rose Bengal dye under visible light irradiation

NASA Astrophysics Data System (ADS)

Kamaraj, Eswaran; Somasundaram, Sivaraman; Balasubramani, Kavitha; Eswaran, Muthu Prema; Muthuramalingam, Rajarajan; Park, Sanghyuk

2018-03-01

A p-type CuO/n-type Pb2O3 heterojunction photocatalyst was prepared by a simple wet chemical process and the photocatalytic ability was evaluated for the degradation of Rose Bengal (RB) under visible light irradiation. Synthesized nanocatalysts were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS). The p-n heterojunction of CuO-Pb2O3 nanostructures can promote the light absorption capability of photocatalyst and charge separation of electron-hole pairs. Photodegradation assays showed that the addition of CuO effectively enhanced the photocatalytic activity of CuO-Pb2O3 under visible light irradiation (λmax > 420 nm). Compared with pure Pb2O3 and CuO, the CuO-Pb2O3 exhibited significantly enhanced photocatalytic degradation activity. The reaction rate constant of CuO-Pb2O3 is 0.092 min-1, which is much higher than those of CuO (0.073 min-1) and Pb2O3 (0.045 min-1).

Modified solvothermal synthesis of cobalt ferrite (CoFe2O4) magnetic nanoparticles photocatalysts for degradation of methylene blue with H2O2/visible light

NASA Astrophysics Data System (ADS)

Kalam, Abul; Al-Sehemi, Abdullah G.; Assiri, Mohammed; Du, Gaohui; Ahmad, Tokeer; Ahmad, Irfan; Pannipara, M.

2018-03-01

Different grads of magnetic nano-scaled cobalt ferrites (CoFe2O4) photocatalysts were synthesized by modified Solvothermal (MST) process with and without polysaccharide. The indigenously synthesized photocatalysts were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermo gravimetric analysis (TGA), Fourier transform infrared (FT-IR), UV-visible (UV-vis) spectroscopy and N2 adsorption-desorption isotherm method. The Fourier transform infrared spectroscopy study showed the Fe-O stretching vibration 590-619 cm-1, confirming the formation of metal oxide. The crystallite size of the synthesized photocatalysts was found in the range between 20.0 and 30.0 nm. The surface area of obtained magnetic nanoparticles is found to be reasonably high in the range of 63.0-76.0 m2/g. The results shown that only MST-2 is the most active catalyst for photo-Fenton like scheme for fast photodegradation action of methylene blue dye, this is possible due to optical band gap estimated of 2.65 eV. Captivatingly the percentage of degradation efficiency increases up to 80% after 140 min by using MST-2 photocatalyst. Photocatalytic degradation of methylene blue (MB) dye under visible light irradiation with cobalt ferrite magnetic nanoparticles followed first order kinetic constant and rate constant of MST-2 is almost 2.0 times greater than MST-1 photocatalyst.

[Experimental research of turbidity influence on water quality monitoring of COD in UV-visible spectroscopy].

PubMed

Tang, Bin; Wei, Biao; Wu, De-Cao; Mi, De-Ling; Zhao, Jing-Xiao; Feng, Peng; Jiang, Shang-Hai; Mao, Ben-Jiang

2014-11-01

Eliminating turbidity is a direct effect spectroscopy detection of COD key technical problems. This stems from the UV-visible spectroscopy detected key quality parameters depend on an accurate and effective analysis of water quality parameters analytical model, and turbidity is an important parameter that affects the modeling. In this paper, we selected formazine turbidity solution and standard solution of potassium hydrogen phthalate to study the turbidity affect of UV--visible absorption spectroscopy detection of COD, at the characteristics wavelength of 245, 300, 360 and 560 nm wavelength point several characteristics with the turbidity change in absorbance method of least squares curve fitting, thus analyzes the variation of absorbance with turbidity. The results show, In the ultraviolet range of 240 to 380 nm, as the turbidity caused by particle produces compounds to the organics, it is relatively complicated to test the turbidity affections on the water Ultraviolet spectra; in the visible region of 380 to 780 nm, the turbidity of the spectrum weakens with wavelength increases. Based on this, this paper we study the multiplicative scatter correction method affected by the turbidity of the water sample spectra calibration test, this method can correct water samples spectral affected by turbidity. After treatment, by comparing the spectra before, the results showed that the turbidity caused by wavelength baseline shift points have been effectively corrected, and features in the ultraviolet region has not diminished. Then we make multiplicative scatter correction for the three selected UV liquid-visible absorption spectroscopy, experimental results shows that on the premise of saving the characteristic of the Ultraviolet-Visible absorption spectrum of water samples, which not only improve the quality of COD spectroscopy detection SNR, but also for providing an efficient data conditioning regimen for establishing an accurate of the chemical measurement methods.

TiO2-BASED Composite Films for the Photodegradation of Oxytetracycline

NASA Astrophysics Data System (ADS)

Li, Hui; Guan, Ling-Xiao; Feng, Ji-Jun; Li, Fang; Yao, Ming-Ming

2015-02-01

The spread of the antibiotic oxytetracycline (OTC) has been thought as a threat to the safety of drinking water. In this paper, the photocatalytic activity of the nanocrystalline Fe/Ca co-doped TiO2-SiO2 composite film for the degradation of OTC was studied. The films were characterized by field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive spectroscopy (EDS), N2 adsorption/desorption isotherms, photoluminescence (PL) spectra, and UV-Vis diffraction reflectance absorption spectra (DRS). The FE-SEM results indicated that the Fe/Ca co-doped TiO2-SiO2 film was composed of smaller nanoparticles compared to pure TiO2 or TiO2-SiO2 film. The BET surface area results showed that the specific surface area of the pure TiO2, TiO2-SiO2 and Ca2+/Fe3+ co-doped TiO2-SiO2 is 118.3 m2g-1, 294.3 m2g-1 and 393.7 m2g-1, respectively. The DRS and PL spectra revealed that the Fe/Ca co-doped TiO2-SiO2 film had strong visible light adsorption and diminished electrons/holes recombination. Experimental results showed that the Fe/Ca co-doped TiO2-SiO2 film is effective in the degradation of OTC under both UV and visible light irradiation.

Biosynthesis of palladium nanoparticles using Saccharomyces cerevisiae extract and its photocatalytic degradation behaviour

NASA Astrophysics Data System (ADS)

Sriramulu, Mohana; Sumathi, Shanmugam

2018-06-01

In this article, we have discussed the biosynthesis of palladium nanoparticles (PdNPs) using aqueous Saccharomyces cerevisiae extract and its photocatalytic application. The biosynthesised PdNPs were characterised by UV-Vis spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and Atomic force microscopy (AFM). The formation of PdNPs was confirmed from the disappearance of the peak at 405 nm in the UV-Vis spectrum. Agglomerated and hexagonal shaped PdNPs were noted by SEM. FTIR was performed to identify the biomolecules responsible for the synthesis of PdNPs. Bioactive compounds in the yeast extract acted as secondary metabolites which facilitated the formation of PdNPs. The yeast synthesised PdNPs degraded 98% of direct blue 71 dye photochemically within 60 min under UV light.

TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: a comparative study of photo catalysis on acid red 88.

PubMed

Balachandran, K; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P

2014-07-15

A novel, simple, less time-consuming and cost-effective wet chemical technique was used to synthesis TiO2 nanoparticles and TiO2-SiO2 nanocomposites using Titanium tetra isopropoxide (TTIP) as a precursor relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of TTIP and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6h and dried at room temperature. The resulting powders were characterized by UV-Visible spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM). The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy-energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy. Surface area of the composite as calculated by BET analyzer and it was found to be 65 and 75 m(2)/g for TiO2 and TiO2-SiO2 respectively. The photocatalytic experiments were performed with aqueous solution of acid red 88 with TiO2 and TiO2-SiO2 batch studies for 4h irradiation, direct photolysis of TiO2 and TiO2-SiO2 contributed 94.2% and 96.5% decomposition in solar radiation for the optimized concentration of acid red 88. Copyright © 2014 Elsevier B.V. All rights reserved.

PAMAM templated N,Pt co-doped TiO2 for visible light photodegradation of brilliant black.

PubMed

Nzaba, Sarre Kadia Myra; Ntsendwana, Bulelwa; Mamba, Bhekie Brilliance; Kuvarega, Alex Tawanda

2018-05-01

This study examined the photocatalytic degradation of an azo dye brilliant black (BB) using non-metal/metal co-doped TiO 2 . N,Pt co-doped TiO 2 photocatalysts were prepared by a modified sol-gel method using amine-terminated polyamidoamine dendrimer generation 0 (PG0) as a template and source of nitrogen. Structural, morphological, and textural properties were evaluated using scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy (SEM/EDX), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR), Raman spectroscopy (RS), photoluminescence (PL) and ultra-violet/visible spectroscopy (UV-Vis). The synthesized photocatalysts exhibited lower band gap energies as compared to the Degussa P-25, revealing a red shift in band gap towards the visible light absorption region. Photocatalytic activity of N,Pt co-doped TiO 2 was measured by the reaction of photocatalytic degradation of BB dye. Enhanced photodegradation efficiency of BB was achieved after 180-min reaction time with an initial concentration of 50 ppm. This was attributed to the rod-like shape of the materials, larger surface area, and enhanced absorption of visible light induced by N,Pt co-doping. The N,Pt co-doped TiO 2 also exhibited pseudo-first-order kinetic behavior with half-life and rate constant of 0.37 and 0.01984 min -1 , respectively. The mechanism of the photodegradation of BB under the visible light irradiation was proposed. The obtained results prove that co-doping of TiO 2 with N and Pt contributed to the enhanced photocatalytic performances of TiO 2 for visible light-induced photodegradation of organic contaminants for environmental remediation. Therefore, this work provides a new approach to the synthesis of PAMAM templated N,Pt co-doped TiO 2 for visible light photodegradation of brilliant black.

Piper betle-mediated synthesis, characterization, antibacterial and rat splenocyte cytotoxic effects of copper oxide nanoparticles.

PubMed

Praburaman, Loganathan; Jang, Jum-Suk; Muthusamy, Govarthanan; Arumugam, Sengottaiyan; Manoharan, Koildhasan; Cho, Kwang-Min; Min, Cho; Kamala-Kannan, Seralathan; Byung-Taek, Oh

2016-09-01

The study reports a simple, inexpensive, and eco-friendly synthesis of copper oxide nanoparticles (CuONPs) using Piper betle leaf extract. Formation of CuONPs was confirmed by UV-visible spectroscopy at 280 nm. Transmission electron microscopy (TEM) images showed that the CuONPs were spherical, with an average size of 50-100 nm. The scanning electron microscopy (SEM)-energy dispersive spectroscopy (EDS) peak was observed approximately at 1 and 8 keV. The X-ray diffraction (XRD) studies indicated that the particles were crystalline in nature. CuONPs effectively inhibited the growth of phytopathogens Ralstonia solanacearum and Xanthomonas axonopodis. The cytotoxic effect of the synthesized CuONPs was analyzed using rat splenocytes. The cell viability was decreased to 94% at 300 μg/mL.

Ag-doped CdO nanocatalysts: Preparation, characterization and catechol oxidase activity

NASA Astrophysics Data System (ADS)

El-Kemary, Maged; El-Mehasseb, Ibrahim; El-Shamy, Hany

2018-06-01

Silver doped cadmium oxide (Ag/CdO) nanoparticles with an average size of 41 nm have been successfully synthesized via thermal decomposition and liquid impregnation technique. The structural characterization has been performed by using several spectroscopic techniques, e.g., X-ray diffraction (XRD), scanning electron microscopy (SEM) and fourier-transform infrared (FT-IR). The catechol oxidase has been studied by UV-visible absorption spectroscopy and fourier-transform infrared as well as the mechanism has been assured by cyclic voltammetry and fluorescence spectroscopy. The results indicate that the oxidation does not occur in the presence of unsupported cadmium oxide particles by silver and in the same time, the catechol oxidase activity of silver doped CdO nanoparticles were improved by about three orders of magnitude than silver ions.

Synthesis and characterization of monodispersed polymer/polydiacetylene nanocrystal composite particles.

PubMed

Wei, Zhong; Ujiiye-Ishii, Kento; Masuhara, Akito; Kasai, Hitoshi; Okada, Shuji; Matsune, Hideki; Asahi, Tsuyoshi; Masuhara, Hiroshi; Nakanishi, Hachiro

2005-06-01

Monodispersed polymer/polydiacetylenecomposite particles were synthesized by soap-free seeded emulsion polymerization of styrene andmethyl methacrylate; the products were characterized by XRD, SEM, TEM, UV-visible spectroscopy, and single particle scattering spectroscopy. In the synthesis process, polydiacetylene nanocrystals were found to act as inhibitor, and consequently a relatively low concentration was necessary. Different monomers lead to the differences in reaction condition and particle morphology; the PMMA composite particles were simpler in preparation than polystyrene particles, but the latter havebetter spherical morphology. The composite particles were composed of polymer shells and polydiacetylene cores, which kept their crystal structure and optical properties. A high percentage of cored particles could be achieved with optimized reaction conditions where the amount of seed was sufficient and the oily oligomer by-product was suppressed.

Microstructural and optical properties of Mn doped NiO nanostructures synthesized via sol-gel method

NASA Astrophysics Data System (ADS)

Shah, Shamim H.; Khan, Wasi; Naseem, Swaleha; Husain, Shahid; Nadeem, M.

2018-04-01

Undoped and Mn(0, 5%, 10% and 15%) doped NiO nanostructures were synthesized by sol-gel method. Structure, morphology and optical properties were investigated through XRD, FTIR, SEM/EDS and UV-visible absorption spectroscopy techniques. XRD data analysis reveals the single phase nature with cubic crystal symmetry of the samples and the average crystallite size decreases with the doping of Mn ions upto 10%. FTIR spectra further confirmed the purity and composition of the synthesized samples. The non-spherical shape of the nanostructures was observed from SEM micrographs and gain size of the nanostructures reduces with Mn doping in NiO, whereas agglomeration increases in doped sample. Optical band gap was estimated using Tauc'srelation and found to increase on incorporation of Mn upto 10% in host lattice and then decreases for further doping.

Copper Oxide Nanograss for Efficient and Stable Photoelectrochemical Hydrogen Production by Water Splitting

NASA Astrophysics Data System (ADS)

Borkar, Rajnikant; Dahake, Rashmi; Rayalu, Sadhana; Bansiwal, Amit

2018-03-01

A biphasic copper oxide thin film of grass-like appendage morphology is synthesized by two-step electro-deposition method and later investigated for photoelectrochemical (PEC) water splitting for hydrogen production. Further, the thin film was characterized by UV-Visible spectroscopy, x-ray diffraction (XRD), Scanning electron microscopy (SEM) and PEC techniques. The XRD analysis confirms formation of biphasic copper oxide phases, and SEM reveals high surface area grass appendage-like morphology. These grass appendage structures exhibit a high cathodic photocurrent of - 1.44 mAcm-2 at an applied bias of - 0.7 (versus Ag/AgCl) resulting in incident to photon current efficiency (IPCE) of ˜ 10% at 400 nm. The improved light harvesting and charge transport properties of grass appendage structured biphasic copper oxides makes it a potential candidate for PEC water splitting for hydrogen production.

Synthesis of nano-titanium dioxide by sol-gel route

NASA Astrophysics Data System (ADS)

Kaler, Vandana; Duchaniya, R. K.; Pandel, U.

2016-04-01

Nanosized titanium dioxide powder was synthesised via sol-gel route by hydrolysis of titanium tetraisopropoxide with ethanol and water mixture in high acidic medium. The synthesized nanopowder was further characterized by X-ray Diffraction, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and Ultraviolet Visible Spectroscopy in order to determine size, morphology and crystalline structure of the material. The synthesis of nano-TiO2 powder in anatase phase was realized by XRD. The optical studies of nano-TiO2 powder was carried out by UV-Vis spectroscopy and band gap was calculated as 3.5eV, The SEM results with EDAX confirmed that prepared nano-TiO2 particles were in nanometer range with irregular morphology. The FTIR analysis showed that only desired functional groups were present in sample. These nano-TiO2 particles have applications in solar cells, chemical sensors and paints, which are thrust areas these days.

Biosynthesis, characterization and antimicrobial action of silver nanoparticles from root bark extract of Berberislycium Royle.

PubMed

Mehmood, Ansar; Murtaza, Ghulam; Bhatti, Tariq Mahmood; Kausar, Rehana; Ahmed, Muhammad Jamil

2016-01-01

Various biological methods are being recognized for the fabrication of silver nanoparticles, which are used in several fields. The phytosynthesis of nanoparticles came out as a cost effective and enviro-friendly approach. When root bark extract of Berberis lycium was treated with silver ions, they reduced to silver nanoparticles, which were spherical, crystalline, size ranged from 10-100nm and capped by biomolecules. Synthesized silver nanoparticles were characterized by UV-visible spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and Fourier Transform Infra Red Spectroscopy (FTIR). The plant mediated synthesized silver nanoparticles showed pronounced antimicrobial activities against both Gram negative bacteria (Escherichia coli, Klebseilla pneumoniae, Pseudomonas aeruginosa) and Gram positive bacteria (Staphylococcus aureus and Bacillus subtilis). The plant mediated process proved to be non-toxic and low cost contender as reducing agent for synthesizing stable silver nanoparticles.

Photocatalytic Degradation Effect of μ-Dielectric Barrier Discharge Plasma Treated Titanium Dioxide Nanoparticles on Environmental Contaminant.

PubMed

Seo, Hyeon Jin; Hwang, Ki-Hwan; Na, Young Hoon; Boo, Jin-Hyo

2018-09-01

This study focused on the photocatalytic degradation effect of the μ-dielectric barrier discharge (μ-DBD) plasma treated titanium dioxide (TiO2) nanoparticles on environmental contaminant such as formaldehyde. TiO2 nanoparticles were treated by a μ-DBD plasma source with nitrogen gas. We analyzed the degradation of formaldehyde with the plasma treated TiO2 nanoparticles by UV-visible spectrophotometer (UV-VIS), and demonstrated that the photocatalytic activity of the μ-DBD plasma-treated TiO2 nanoparticles showed significantly high catalytic efficiency rather than without plasma treated TiO2 nanoparticles. Field emission scanning electron microscopes (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and water contact angle analyzer were used to measure the effects of photocatalytic degradation for the plasma treated TiO2 nanoparticles.

Preparation high photocatalytic activity of CdS/halloysite nanotubes (HNTs) nanocomposites with hydrothermal method

NASA Astrophysics Data System (ADS)

Xing, Weinan; Ni, Liang; Huo, Pengwei; Lu, Ziyang; Liu, Xinlin; Luo, Yingying; Yan, Yongsheng

2012-10-01

A novel nanocatalyst CdS/halloysite nanotubes (HNTs) was synthesized by hydrothermal method with direct growth of CdS nanoparticles on the surface of HNTs. The as-prepared photocatalysts had been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis DRS), Fourier transform infrared (FT-IR) and the thermo gravimetric analysis (TGA). The photocatalytic activity of the sample was evaluated by the degradation of tetracycline (TC) under visible light irradiation. Benefit from the excellent properties of CdS and HNTs, the photocatalyst exhibited good photocatalytic activity and stability. In order to find out the optimum synthesis condition to obtain the best photocatalytic activity, a series of experiments were performed with different CdS loading capacity, different sources of sulfide and different hydrothermal temperatures, etc. The best photodegradation rate could reach 93% in 60 min under visible light irradiation. Therefore, the combination of CdS nanoparticles with HNTs endowed this material with a potential use in environmental treatments in industries.

A novel hydroxyl epoxy phosphate monomer enhancing the anticorrosive performance of waterborne Graphene/Epoxy coatings

NASA Astrophysics Data System (ADS)

Ding, Jiheng; Rahman, Obaid ur; Peng, Wanjun; Dou, Huimin; Yu, Haibin

2018-01-01

Herein, we report the synthesis of a novel hydroxyl epoxy phosphate monomer (PGHEP) as an efficient dispersant for graphene to enhance the compatibility of the graphene in epoxy resin. Raman spectroscopy, Ultraviolet-visible spectroscopy (UV-vis) and X-ray photoelectron spectroscopy (XPS) studies were confirmed the π-π interactions between PGHEP and graphene. Well-dispersed states of PGHEP functionalized graphene (G) sheets in water were analyzed by transmission electron microscopy (TEM), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Further, microstructure of prepared G/waterborne epoxy coatings containing 0.5-1.0 wt.% of PGHEP functionalized G sheets were also observed with the help of SEM and TEM. The PGHEP functionalized G sheets dispersed composite coatings displayed enhanced corrosion resistance compared with pure epoxy resin, these coatings have higher contact angle, lower water absorption as evident from the results of electrochemical impedance spectroscopy (EIS) and salt spray tests. The superior corrosion protection performances of G/epoxy coatings were mainly attributed to the formed passive film from uniformly dispersed PGHEP functionalized G sheets which act as physical barrier on the steel surface. Therefore, this work provides a novel bio-based efficient dispersant for G sheets and an important method for preparing G/waterborne epoxy coatings with superior corrosion resistance properties.

Highly efficient Zr doped-TiO2/glass fiber photocatalyst and its performance in formaldehyde removal under visible light.

PubMed

Huang, Chao; Ding, Yaping; Chen, Yingwen; Li, Peiwen; Zhu, Shemin; Shen, Shubao

2017-10-01

Zr-doped-TiO 2 loaded glass fiber (ZT/GF) composite photocatalysts with different Zr/Ti ratios were prepared with a sol-gel process. Zr 4+ can replace Ti 4+ in the TiO 2 lattice, which is conducive to forming the anatase phase and reducing the calcination temperature. The glass fiber carrier was responsible for better dispersion and loading of Zr-doped-TiO 2 particles, improving the applicability of the Zr-doped-TiO 2 . The ZT/GF photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis) and Barrett-Joyner-Halenda (BJH). The performance of photocatalysts with different loading was evaluated in formaldehyde degradation under visible light at room temperature. ZT/GF0.2 exhibited the highest activity, with a formaldehyde removal rate as high as 95.14% being observed, which is better than that of the photocatalyst particles alone. The stability of the catalyst was also tested, and ZT/GF exhibited excellent catalytic performance with 94.38% removal efficiency, even after seven uses. Copyright © 2017. Published by Elsevier B.V.

Facile Synthesis of g-C3N4 Nanosheets/ZnO Nanocomposites with Enhanced Photocatalytic Activity in Reduction of Aqueous Chromium(VI) under Visible Light

PubMed Central

Yuan, Xiaoya; Zhou, Chao; Jing, Qiuye; Tang, Qi; Mu, Yuanhua; Du, An-ke

2016-01-01

Graphitic-C3N4 nanosheets (CN)/ZnO photocatalysts (CN/ZnO) with different CN loadings were successfully prepared via a simple precipitation-calcination in the presence of exfoliated C3N4 nanosheets. Their morphology and structure were thoroughly characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL). The results showed that hexagonal wurzite-phase ZnO nanoparticles were randomly distributed onto the CN nanosheets with a well-bonded interface between the two components in the CN/ZnO composites. The performance of the photocatalytic Cr(VI) reduction indicated that CN/ZnO exhibited better photocatalytic activity than pure ZnO under visible-light irradiation and the photocatalyst composite with a lower loading of CN sheets eventually displayed higher activity. The enhanced performance of CN/ZnO photocatalysts could be ascribed to the increased absorption of the visible light and the effective transfer and separation of the photogenerated charge carriers. PMID:28335301

Citrus maxima (Pomelo) juice mediated eco-friendly synthesis of ZnO nanoparticles: Applications to photocatalytic, electrochemical sensor and antibacterial activities

NASA Astrophysics Data System (ADS)

Pavithra, N. S.; Lingaraju, K.; Raghu, G. K.; Nagaraju, G.

2017-10-01

In the present work, Zinc oxide nanoparticles (ZnO Nps) have been successfully prepared through a simple, effective and low cost solution combustion method using Zn (NO3)2·6H2O as an oxidizer, chakkota (Common name = Pomelo) fruit juice as novel fuel. X-ray diffraction pattern indicates the hexagonal wurtzite structure with average crystallite size of 22 nm. ZnO Nps were characterized with the aid of different spectroscopic techniques such as Raman spectroscopy, Fourier Transform Infrared spectroscopy, Photoluminescence and UV-Visible spectroscopy. FTIR shows characteristic ZnO vibrational mode at 393 cm- 1. SEM images show that the particles are agglomerated. TEM image shows the size of the particles are about 10-20 nm. Further, in order to establish practical applicability of the synthesized ZnO Nps, photocatalytic degradation of methylene blue (MB) dye as a model system was studied in presence of UV (665 nm) light. In addition to this, the antibacterial activity was screen against 3 bacterial strains and electrochemical sensor performance towards the quantification of dopamine at nano molar concentrations was also explored.

Fabrication of meso-porous BiOI sensitized zirconia nanoparticles with enhanced photocatalytic activity under simulated solar light irradiation

NASA Astrophysics Data System (ADS)

Vignesh, K.; Suganthi, A.; Min, Bong-Ki; Kang, Misook

2015-01-01

In this present work, BiOI sensitized zirconia (BiOI-ZrO2) nanoparticles were fabricated using a precipitation-deposition method. The physicochemical characteristics of BiOI/ZrO2 were studied through X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), BET-surface area, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis-DRS) and photoluminescence (PL) spectroscopy techniques. The absorption maximum of ZrO2 was shifted to the visible region after sensitization with BiOI. BET-surface area results inferred that the prepared hetero-junctions were meso-porous in nature. The photocatalytic activity of BiOI-ZrO2 for the degradation of methyl violet (MV) dye under simulated solar light irradiation was investigated in detail. 3% BiOI-ZrO2 exhibited the highest photocatalytic performance (98% of MV degradation) when compared with ZrO2 and BiOI. The enhancement in the photocatalytic activity of BiOI-ZrO2 is ascribed to the sensitization effect of BiOI, suppression of electron-hole recombination and the formation of p-n hetero-junction.

Novel synthesis and characterization of pristine Cu nanoparticles for the non-enzymatic glucose biosensor.

PubMed

Dayakar, T; Rao, K Venkateswara; Bikshalu, K; Rajendar, V; Park, Si-Hyun

2017-07-01

Non enzymatic electrochemical glucose sensing was developed based on pristine Cu Nanopartilces (NPs)/Glassy Carbon Electrode (GCE) which can be accomplished by simple green method via ocimum tenuiflorum leaf extract. Then, the affect of leaf extract addition on improving Structural, Optical and electrochemical properties of pristine cu NPs was investigated. The synthesized Cu NPs were characterized with X-ray diffraction (X-ray), Uv-Visible spectroscopy (Uv-Vis), Fourier transformation infrared spectroscopy (FTIR), Particle size distribution (PSA), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM) for structural optical and morphological studies respectively. The synthesized Cu NPs were coated over glassy carbon electrode (GCE) to study the electrochemical response of glucose by cyclic voltammetry and ampherometer. The results indicates that the modified biosensor shows a remarkable sensitivity (1065.21 μA mM -1  cm -2 ), rapid response time (<3s), wide linear range (1 to 7.2 mM), low detection limit (0.038 μM at S/N = 3). Therefore, the prepared Cu NPs by the Novel Bio-mediated route were exploited to construct a non-enzymatic glucose biosensor for sustainable clinical field applications.

Green synthesis of silver nanoparticles using tannins

NASA Astrophysics Data System (ADS)

Raja, Pandian Bothi; Rahim, Afidah Abdul; Qureshi, Ahmad Kaleem; Awang, Khalijah

2014-09-01

Colloidal silver nanoparticles were prepared by rapid green synthesis using different tannin sources as reducing agent viz. chestnut (CN), mangrove (MG) and quebracho (QB). The aqueous silver ions when exposed to CN, MG and QB tannins were reduced which resulted in formation of silver nanoparticles. The resultant silver nanoparticles were characterized using UV-Visible, X-ray diffraction (XRD), scanning electron microscopy (SEM/EDX), and transmission electron microscopy (TEM) techniques. Furthermore, the possible mechanism of nanoparticles synthesis was also derived using FT-IR analysis. Spectroscopy analysis revealed that the synthesized nanoparticles were within 30 to 75 nm in size, while XRD results showed that nanoparticles formed were crystalline with face centered cubic geometry.

Acoustical, morphological and optical properties of oral rehydration salts (ORS)

NASA Astrophysics Data System (ADS)

George, Preetha Mary; Jayakumar, S.; Divya, P.; Subhashree, N. S.; Ahmed, M. Anees

2015-06-01

Ultrasonic velocity, density and viscosity were measured in different concentrations of oral rehydration salts (ORS) at room temperature 303 k. From the experimental data other related thermodynamic parameters, viz adiabatic compressibility, intermolecular free length, acoustic impedence, relaxation time are calculated. The experimental data were discussed in the light of molecular interaction existing in the liquid mixtures. The results have been discussed in terms of solute-solvent interaction between the components. Structural characterization is important for development of new material. The morphology, structure and grain size of the samples are investigated by SEM. The optical properties of the sample have been studied using UV Visible spectroscopy.

Structural, optical and morphological characterization of Cu-doped α-Fe2O3 nanoparticles synthesized through co-precipitation technique

NASA Astrophysics Data System (ADS)

Lassoued, Abdelmajid; Lassoued, Mohamed Saber; Dkhil, Brahim; Gadri, Abdellatif; Ammar, Salah

2017-11-01

Pure and copper (Cu concentration varying from 2 to 8%) doped hematite (α-Fe2O3) nanocrystals were synthesized through co-precipitation method using simple equipment. X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR), Raman spectroscopy, Differential Thermal Analysis (DTA), Thermo Gravimetric Analysis (TGA) and Ultraviolet-Visible (UV-Vis) techniques were used to characterize the synthesized samples. XRD measurements confirm that all the prepared nanocrystals consist only in nanocrystalline hematite phase. These results along with TEM and SEM show that the size of the nanoparticles decreases with Cu-doping down to 21 nm. FT-IR confirm the phase purity of the nanoparticles synthesized. The Raman spectroscopy was used not only to prove that we synthesized pure and Cu-doped hematite but also to identify their phonon modes. The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. The UV-Vis absorption measurements confirm that the decrease of particle size is accompanied by a decrease in the band gap value from 2.12 eV for pure α-Fe2O3 down to 1.91 eV for 8% Cu-doped α-Fe2O3. 8% Cu-doped hematite had the smallest size, the best crystallinity and the lowest band gap.

Surface active gold nanoparticles biosynthesis by new approach for bionanocatalytic activity.

PubMed

Vasantharaj, S; Sripriya, N; Shanmugavel, M; Manikandan, E; Gnanamani, A; Senthilkumar, P

2018-02-01

In the present day, nanotechnology is one of the most promising leading scientific and potentials areas in modern key technology development toward to the humankind. The synthesis of noble metal nanoparticles (NPs) is an expanding research area due to the possible applications for the development of bio-medical applications. Eco-friendly approach for the biosynthesis of gold nanoparticles (AuNPs) using the aqueous extract from Ruellia tuberosa and Phyllanthus acidus (leaf and twig) for the first time. Surface active AuNPs were characterized by UV-Vis spectroscopy, FTIR (Fourier transform infrared) spectroscopy, DSC (differential scanning colorimetry), DLS (dynamic light scattering) and environmental SEM (scanning electron microscope) analysis at room temperature (RT). Enhanced surface plasmon resonance (SPR) absorbance UV visible optical spectra were detected in the range of 552, 548, 558 and 536 nm. SEM and DLS (transmission mode) analysis confirmed the morphology of the nanoparticles to be spherical with the average size in the range of 88.37, 94.31, 82.23 and 81.36 nm. Further they have enhanced the enzyme activity on α-amylase, cellulase, and xylanase. The results suggest that the phyto-fabricated AuNPs from R. tuberosa and P. acidus is simple, less expensive, eco-friendly, green synthesis and also can be exploited for the potential future industrial and bio-medical applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhanced photocatalytic activity of Bi2WO6/TiO2 composite coated polyester fabric under visible light irradiation

NASA Astrophysics Data System (ADS)

Du, Zoufei; Cheng, Cheng; Tan, Lin; Lan, Jianwu; Jiang, Shouxiang; Zhao, Ludan; Guo, Ronghui

2018-03-01

In this study, a visible-light-driven photocatalyst Bi2WO6/TiO2 composite was reported using one-step hydrothermal method and then coated on the polyester fabric. The samples were systematically characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, UV-vis diffuse reflection spectroscopy and photoluminescence spectroscopy (PL). The photocatalytic activity of Bi2WO6/TiO2 coated polyester fabric was evaluated by degradation of Rhodamine B (RhB) and Methylene blue (MB) under visible light irradiation. The self-cleaning property of the fabrics was assessed through removing red wine stain. The results reveal that the Bi2WO6/TiO2 composites with irregular shape are coated on the polyester fabric successfully. The UV-vis absorption spectra show a broad absorption band in the visible region, which extends the scope of absorption spectrum and helps to improve the photocatalytic degradation efficiency. Photocatalytic activities of the Bi2WO6/TiO2 composite polyester fabric are associated with the content of TiO2. Bi2WO6/15%TiO2 coated polyester fabric exhibits the degradation efficiency for RhB and MB up to 98% and 95.1%, respectively, which is much higher than that of pure Bi2WO6 and TiO2 coated polyester fabric. Moreover, Bi2WO6/15%TiO2 coated polyester fabric shows good cycle stability toward continuous three cycles of photocatalytic experiment for dyes degradation. In addition, the Bi2WO6/TiO2 coated polyester fabric shows good self-cleaning property. This work could be extended to design of other composite photocatalyst coating on the fabric for enhancing activity by coupling suitable wide and narrow band-gap semiconductors.

Optical properties of ZnO/BaCO3 nanocomposites in UV and visible regions.

PubMed

Zak, Ali Khorsand; Hashim, Abdul Manaf; Darroudi, Majid

2014-01-01

Pure zinc oxide and zinc oxide/barium carbonate nanoparticles (ZnO-NPs and ZB-NPs) were synthesized by the sol-gel method. The prepared powders were characterized by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Auger spectroscopy, and transmission electron microscopy (TEM). The XRD result showed that the ZnO and BaCO3 nanocrystals grow independently. The Auger spectroscopy proved the existence of carbon in the composites besides the Zn, Ba, and O elements. The UV-Vis spectroscopy results showed that the absorption edge of ZnO nanoparticles is redshifted by adding barium carbonate. In addition, the optical parameters including the refractive index and permittivity of the prepared samples were calculated using the UV-Vis spectra. 81.05.Dz; 78.40.Tv; 42.70.-a.

Ultraviolet-Visible and Fluorescence Spectroscopy Techniques Are Important Diagnostic Tools during the Progression of Atherosclerosis: Diet Zinc Supplementation Retarded or Delayed Atherosclerosis

PubMed Central

Abdelhalim, Mohamed Anwar K.; Moussa, Sherif A. Abdelmottaleb; AL-Mohy, Yanallah Hussain

2013-01-01

Background. In this study, we examined whether UV-visible and fluorescence spectroscopy techniques detect the progression of atherosclerosis in serum of rabbits fed on high-cholesterol diet (HCD) and HCD supplemented with zinc (HCD + Zn) compared with the control. Methods. The control rabbits group was fed on 100 g/day of normal diet. The HCD group was fed on Purina Certified Rabbit Chow supplemented with 1.0% cholesterol plus 1.0% olive oil (100 g/day) for the same period. The HCD + Zn group was fed on normal Purina Certified Rabbit Chow plus 1.0% cholesterol and 1.0% olive oil supplemented with 470 ppm Zn for the same feeding period. UV-visible and fluorescence spectroscopy and biochemistry in Rabbit's blood serum and blood hematology were measured in Rabbit's blood. Results. We found that the fluorescent peak of HCD shifted toward UV-visible wavelength compared with the control using fluorescent excitation of serum at 192 nm. In addition, they showed that supplementation of zinc (350 ppm) restored the fluorescent peak closely to the control. By using UV-visible spectroscopy approach, we found that the peak absorbance of HCD (about 280 nm) was higher than that of control and that zinc supplementation seemed to decrease the absorbance. Conclusions. This study demonstrates that ultraviolet-visible and fluorescence spectroscopy techniques can be applied as noninvasive techniques on a sample blood serum for diagnosing or detecting the progression of atherosclerosis. The Zn supplementation to rabbits fed on HCD delays or retards the progression of atherosclerosis. Inducing anemia in rabbits fed on HCD delays the progression of atherosclerosis. PMID:24350281

Highly Sensitive NiO Nanoparticle based Chlorine Gas Sensor

NASA Astrophysics Data System (ADS)

Arif, Mohd.; Sanger, Amit; Singh, Arun

2018-03-01

We have synthesized a chemiresistive sensor for chlorine (Cl2) gas in the range of 2-200 ppm based on nickel oxide (NiO) nanoparticles obtained by wet chemical synthesis. The nanoparticles were characterized by x-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and photoluminescence (PL) spectroscopy. XRD spectra of the sensing layer revealed the cubic phase of NiO nanoparticles. The NiO nanoparticle size was calculated to be ˜ 21 nm using a Williamson-Hall plot. The bandgap of the NiO nanoparticles was found to be 3.13 eV using Tauc plots of the absorbance curve. Fast response time (12 s) and optimum recovery time (˜ 27 s) were observed for 10 ppm Cl2 gas at moderate temperature of 200°C. These results demonstrate the potential application of NiO nanoparticles for fabrication of highly sensitive and selective sensors for Cl2 gas.

Growth and characterization of single phase Cu{sub 2}O by thermal oxidation of thin copper films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhary, Sumita; Sarma, J. V. N.; Gangopadhyay, Subhashis, E-mail: subhagan@yahoo.com

2016-04-13

We report a simple and efficient technique to form high quality single phase cuprous oxide films on glass substrate using thermal evaporation of thin copper films followed by controlled thermal oxidation in air ambient. Crystallographic analysis and oxide phase determination, as well as grain size distribution have been studied using X-ray diffraction (XRD) method, while scanning electron microscopy (SEM) has been utilized to investigate the surface morphology of the as grown oxide films. The formation of various copper oxide phases is found to be highly sensitive to the oxidation temperature and a crystalline, single phase cuprous oxide film can bemore » achieved for oxidation temperatures between 250°C to 320°C. Cu{sub 2}O film surface appeared in a faceted morphology in SEM imaging and a direct band gap of about 2.1 eV has been observed in UV-visible spectroscopy. X-ray photoelectron spectroscopy (XPS) confirmed a single oxide phase formation. Finally, a growth mechanism of the oxide film has also been discussed.« less

Preparation and characterization of PVP-PVA–ZnO blend polymer nano composite films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Divya, S., E-mail: divi.fysics@gmail.com; Saipriya, G.; Hemalatha, J., E-mail: hemalatha@nitt.edu

Flexible self-standing films of PVP-PVA blend composites are prepared by using ZnO as a nano filler at different concentrations. The structural, compositional, morphological and optical studies made with the help of X-ray diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FTIR), Scanning electron microscope (SEM), Atomic Force Microscopy (AFM), Ultraviolet-visible spectroscopy (UV-vis) and Photoluminescence (PL) spectra are presented in this paper. The results of XRD indicate that ZnO nanoparticles are formed with hexagonal phase in the polymeric matrix. SEM images show the dispersion of ZnO nano filler in the polymer matrix. UV–vis spectra reveal that the absorption peak is centered around 235more » nm and 370 nm for the nano composite films. The blue shift is observed with decrease in the concentration of the nano filler. PL spectra shows the excitation wavelength is given at 320 nm.The emission peaks were observed at 383 nm ascribing to the electronic transitions between valence band and conduction band and the peak at 430 nm.« less

Ultraviolet and visible light spectrophotometric approach to blood typing: objective analysis by agglutination index.

PubMed

Narayanan, S; Orton, S; Leparc, G F; Garcia-Rubio, L H; Potter, R L

1999-10-01

A new blood typing technology based on ultraviolet (UV) and visible light spectroscopy (UV/visible spectroscopy) has been developed. Blood groups and types are determined by quantifying reproducible changes in the UV and visible light spectra of blood in the presence of agglutinating antibodies. Samples of red cells in the presence and absence of agglutinating antibodies were examined by UV/visible spectroscopy. Blood groups and types were determined by comparing the optical density spectra obtained between 665 and 1000 nm. These comparisons generate numbers (agglutination index) ranging from 0 to 100, with smaller numbers corresponding to lack of agglutination and larger numbers corresponding to agglutination. The optical density of agglutinated blood is dramatically different from that of unagglutinated blood. The agglutination index derived from the relative slopes of the spectra is an objective indicator of agglutination strength. An agglutination index greater than 17 consistently and accurately established blood group- and type-specific agglutination. The method accurately predicted A, B, and O blood groups, and D type in over 275 samples. Scattering theory-based calculations of relative volumes of red cells before and after agglutination show a direct correlation with the agglutination index and provide the theoretical basis of the analysis. This quantitative technique is reproducible and has the potential for automation.

Pronounced effects of the nominal concentrations of WO3 and Ag: WO3 nano-plates (obtained by a co-precipitation method) on their structural, morphological and optical properties

NASA Astrophysics Data System (ADS)

Rajendran, V.; Deepa, B.

2018-03-01

Tungsten oxide and different concentration of silver (Ag)-doped tungsten oxide nano material were synthesized by co-precipitation technique. The functional vibrations, structure, and morphology of as-prepared nano material were studied by Fourier transmission infrared spectroscopy, X-ray diffraction, scanning electron microscopy (SEM) and High-resolution transmission electron microscopy (HR-TEM) techniques. The SEM and HR-TEM analysis revealed the formation of nano-plate/nano rods with an average diameter of 40-80 nm diameter and 1-1.5 mm length. Fluorescence (PL) and UV-visible absorption techniques have been used to study the optical properties of the prepared nanoparticles. The observed red shift in the visible absorption spectra confirmed the promoted electron-phonon interaction in WO3 and Ag: WO3 nanoparticles compared to bulk structures. The photoluminescence of nanocrystalline Ag2+ doped WO3 exhibited a strong violet-blue, blue-green emission. Concentration dependence of the emission intensity of Ag2+ in WO3 was studied, and the significant concentration was found to be 0.5% of Ag: WO3. The effluent dye degradation executed for the 0.5% of Ag: WO3 sample under the visible light which reveals the highest degradation efficiency in appropriate time.

DeNOx Abatement over Sonically Prepared Iron-Substituted Y, USY and MFI Zeolite Catalysts in Lean Exhaust Gas Conditions

PubMed Central

Stachurska, Patrycja; Kuterasiński, Łukasz; Dziedzicka, Anna; Górecka, Sylwia; Chmielarz, Lucjan; Łojewska, Joanna; Sitarz, Maciej

2018-01-01

Iron-substituted MFI, Y and USY zeolites prepared by two preparation routes—classical ion exchange and the ultrasound modified ion-exchange method—were characterised by micro-Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet (UV)/visible diffuse reflectance spectroscopy (UV/Vis DRS). Ultrasound irradiation, a new technique for the preparation of the metal salt suspension before incorporation to the zeolite structure, was employed. An experimental study of selective catalytic reduction (SCR) of NO with NH3 on both iron-substituted reference zeolite catalysts and those prepared through the application of ultrasound conducted during an ion-exchange process is presented. The prepared zeolite catalysts show high activity and selectivity in SCR deNOx abatement. The MFI-based iron catalysts, especially those prepared via the sonochemical method, revealed superior activity in the deNOx process, with almost 100% selectivity towards N2. The hydrothermal stability test confirmed high stability and activity of MFI-based catalysts in water-rich conditions during the deNOx reaction at 450 °C. PMID:29301370

Novel Bi/BiOBr/AgBr composite microspheres: Ion exchange synthesis and photocatalytic performance

NASA Astrophysics Data System (ADS)

Lyu, Jianchang; Li, Zhenlu; Ge, Ming

2018-06-01

Novel Bi/BiOBr/AgBr composite microspheres were prepared by a rational in situ ion exchange reaction between Bi/BiOBr microspheres and AgNO3. The characteristic of the as-obtained ternary microspheres was tested by X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL). Under visible light irradiation, Bi/BiOBr/AgBr microspheres exhibited an excellent photocatalytic efficiency for rhodamine B (RhB) degradation, which was about 1.4 and 4.9 times as high as that of Bi/BiOBr and BiOBr/AgBr, demonstrating that the highest separation efficiency of charge carriers in the heterostructured Bi/BiOBr/AgBr. The photocatalytic activity of Bi/BiOBr/AgBr microspheres just exhibited a slight decrease after three consecutive cycles. The photocatalytic mechanism investigation confirmed that the superoxide radicals (O2•-) were the dominant reactive oxygen species for RhB degradation in Bi/BiOBr/AgBr suspension.

Cytotoxic effect of silver nanoparticles synthesized from Padina tetrastromatica on breast cancer cell line

NASA Astrophysics Data System (ADS)

Gnana Selvi, B. Clara; Madhavan, J.; Santhanam, Amutha

2016-09-01

In recent years researchers were attracted towards marine sources due to the presence of active components in it. Seaweeds were widely used in pharmaceutical research for their known biological activities. The biological synthesis method of silver nanoparticles (AgNPs) using Padina tetrastromatica seaweed extract and their cytotoxicity against breast cancer MCF-7 cells was reported in this study. The synthesized AgNPs using seaweed extract were subjected to x-ray diffraction, UV-visible spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscope, energy dispersive x-ray, zeta potential to elucidate the structural, morphology, size as well as surface potential parameters. An absorption peak at 430 nm in UV-visible spectrum reveals the excitation and surface plasmon resonance of AgNPs. FE-SEM micrographs exhibits the biosynthesized AgNPs, which are pre-dominantly round shaped and the size ranges between 40-50 nm. The zeta potential value of -27.6 mV confirms the stable nature of biosynthesized silver nanoparticles. Furthermore, the biological synthesized Ag NPs exhibited a dose-dependent cytotoxicity against human breast cancer cell (MCF-7) and the inhibitory concentration (IC50) was found for AgNPs against MCF-7 at 24 h incubation. Biological method of synthesizing silver nanoparticles shows a environmental friendly property which helps in effective electrifying usage in many fields.

Preparation and Optical Properties of CuS Nanofilms by a Facile Two-Step Process

NASA Astrophysics Data System (ADS)

Cui, Zhankui; Zhou, Junqiang; Ge, Suxiang; Zhao, Hongxiao

CuS nanofilms were prepared by a facile two-step process including chemical bath deposition of Cu nanofilms first and the subsequent thermal sulfuration step. The composition and structure of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Raman spectroscopy. The optical properties of CuS nanofilms were determined by Ultraviolet-visible (UV-Vis) technique. The results show that the nanofilms composed by Cu spherical nanoparticles were completely transformed to the nanofilms composed by CuS nanosheets when the sulfuration temperature was 350∘C. The light absorption edges of CuS nanofilms exhibit red shift when sulfuration occurred at lower temperature. A plausible growth mechanism related with gas phase reaction for formation of CuS nanofilms was also proposed.

Nanocrystalline ZnO as a Visible Active Photocatalyst for the Degradation of Benzene-1,4-diol

NASA Astrophysics Data System (ADS)

Ramachandran, Saranya; Sivasamy, A.

We have synthesized nanocrystalline ZnO by a simple precipitation method. The prepared ZnO was found to be highly phase pure and nanocrystalline hexagonal wurtzite structure. UV-Visible-DRS spectroscopy showed the material to have bandgap energy of 3.22eV. HR-SEM image revealed the material to be made up of distinct hexagonal particles with a highly porous surface. AFM analysis was employed to confirm the high surface roughness and porosity of the material. The photocatalytic activity of the prepared ZnO was evaluated by the degradation of benzene-1,4-diol (hydroquinone), under visible light irradiation. Preliminary experiments showed the catalyst to be effective at neutral pH with an optimum catalyst dosage of 4g/L. Kinetic studies showed the degradation reaction to follow pseudo-first-order kinetics. In the presence of commonly used industrial electrolytes, the catalyst exhibited a decrease in efficiency. Reusability studies showed the catalytic efficiency of ZnO to diminish marginally after the third cycle of reuse.

Efficient degradation of Methylene Blue dye over highly reactive Cu doped strontium titanate (SrTiO3) nanoparticles photocatalyst under visible light.

PubMed

Rahman, Qazi Inamur; Ahmad, Musheer; Misra, Sunil Kumar; Lohani, Minaxi

2012-09-01

Visible light induced photocatalysts of Cu doped SrTiO3 (Cu/SrTiO3) nanoparticles with the size -60-75 nm were prepared via facile sol-gel method. The morphological, optical, crystalline properties and compositions of synthesized Cu/SrTiO3 nanoparticles were thoroughly characterized by field emission scanning electron microscopy (FE-SEM), powder X-ray diffraction (XRD), ultra violet-visible spectroscopy (UV-Vis) and energy dispersive X-ray (EDX). A significant red shift in the UV-diffused reflectance spectrum was observed and the absorption edge shifted to visible region by the Cu doping. Surprisingly, the band gap of SrTiO3 was changed from 3.2 eV drop to 2.96 eV. The photocatalytic activity of the synthesized Cu/SrTiO3 nanoparticles was demonstrated for the degradation of Methylene Blue dye under visible light irradiation. The formation of new acceptor region in Cu/SrTiO3 was responsible for high photocatalytic activity of Cu/SrTiO3 nanoparticles. The results showed that the Methylene Blue dye was degraded by -66% within time span of 2 h over the Cu/SrTiO3 nanoparticles. This dye degradation reaction followed the Langmuir-Hinshelwood kinetics and also exhibited first order reaction rate. The calculated rate constant for the degradation reaction following first order kinetics was k = 0.0016 min(-1).

Two-dimensional molybdenum disulphide nanoflakes synthesized by liquid-solid phase reaction method: regenerative photocatalytic performance under UV-visible light irradiation by advance oxidation process

NASA Astrophysics Data System (ADS)

Afsar, M. F.; Rafiq, M. A.; Siddique, Fizza; Saira, F.; Chaudhary, M. M.; Hasan, M. M.; Tok, A. I. Y.

2018-05-01

Molybdenum disulphide (MoS2) nanoflakes were prepared through liquid-solid phase reaction technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM) analysis revealed the formation of pure, polycrystalline, hexagonal phase of MoS2 nanoflakes. The texture coefficient (T{c}hkl) analysis showed that (100) plane was preferentially oriented. The specific surface area of the nanoflakes was 21 m2 g‑1 as determined using Brunaure-Emmett-Teller (BET) technique. A band gap of ∼2.05 eV for MoS2 nanoflakes was estimated from UV-visible spectrum. Regenerative photocatalytic activity of MoS2 nanoflakes was assessed by degrading methylene blue (MB) and safranin-o (SO) dyes under UV-visible light irradiation. Under light irradiation, degradation efficiency for MB was ∼99.58% in 100 min while for SO it was ∼99.89% in 70 min. The MoS2 nanoflakes exhibited excellent photocatalytic performance and good stability in a wide pH range (3–11). MoS2 nanoflakes showed a high reaction rate constant (k app ) for SO ∼ 0.104 49 min‑1 and MB ∼ 0.092 18 min‑1 as compared to other MoS2 nanostructures. The obtained exceptional photocatalytic performance of MoS2 nanoflakes offers potential applications for the treatment of polluted water as well as in other correlated fields.

The use of UV-visible reflectance spectroscopy as an objective tool to evaluate pearl quality.

PubMed

Agatonovic-Kustrin, Snezana; Morton, David W

2012-07-01

Assessing the quality of pearls involves the use of various tools and methods, which are mainly visual and often quite subjective. Pearls are normally classified by origin and are then graded by luster, nacre thickness, surface quality, size, color and shape. The aim of this study was to investigate the capacity of Artificial Neural Networks (ANNs) to classify and estimate the quality of 27 different pearls from their UV-Visible spectra. Due to the opaque nature of pearls, spectroscopy measurements were performed using the Diffuse Reflectance UV-Visible spectroscopy technique. The spectra were acquired at two different locations on each pearl sample in order to assess surface homogeneity. The spectral data (inputs) were smoothed to reduce the noise, fed into ANNs and correlated to the pearl's quality/grading criteria (outputs). The developed ANNs were successful in predicting pearl type, mollusk growing species, possible luster and color enhancing, donor condition/type, recipient/host color, donor color, pearl luster, pearl color, origin. The results of this study shows that the developed UV-Vis spectroscopy-ANN method could be used as a more objective method of assessing pearl quality (grading) and may become a valuable tool for the pearl grading industry.

Synthesis and spectroscopic characterization of gold nanoparticles via plasma-liquid interaction technique

NASA Astrophysics Data System (ADS)

Khatoon, N.; Yasin, H. M.; Younus, M.; Ahmed, W.; Rehman, N. U.; Zakaullah, M.; Iqbal, M. Zafar

2018-01-01

Fabrication of non-functionalized gold nanoparticles is interesting owing to their potential applications in sensing and biomedicine. We report on the synthesis of surfactant-free gold nanoparticles (AuNPs) by Plasma-Liquid Interaction (PLI) technique, using micro-atmospheric pressure D.C. plasma. The effects of discharge parameters, such as discharge current, precursor concentration and gas flow rates on the structure and morphology of AuNPs have been investigated. Optical Emission Spectroscopy (OES) was employed to estimate the UV radiation intensity and OH radical density. Scanning electron microscopy (SEM) and ultraviolet-visible (UV-Vis) optical spectroscopy were employed to study the morphology and structure of AuNPs. The normalized intensities of UV radiation and OH radical density found to increase with increase in discharge current. We observed that the particle size can be tuned by controlling any of the following parameters: intensity of the UV radiation, OH radical density, and concentration of the Au precursor. Interestingly, we found that addition of 1% Ar in the feedstock gas results in formation of relatively uniform size distribution of nanoparticles. The surfactant-free AuNPs, due to their bare-surface, exhibit excellent surface-enhanced Raman scattering (SERS) properties. The SERS study of Rhodamine 6G using AuNPs as substrates, shows significant Raman enhancement and fluorescence quenching, which makes our technique a potentially powerful route to detection of trace amounts of dangerous explosives and other materials.

CTAB assisted synthesis of tungsten oxide nanoplates as an efficient low temperature NOX sensor

NASA Astrophysics Data System (ADS)

Mehta, Swati S.; Tamboli, Mohaseen S.; Mulla, Imtiaz S.; Suryavanshi, Sharad S.

2018-02-01

Tungsten oxide nanoplates with porous morphology were effectively prepared by acidification using CTAB (HexadeCetyltrimethyl ammonium bromide) as a surfactant. For characterization, the synthesized materials were subjected to X-Ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), UV-Visible spectroscopy (UV-Vis) and surface area (BET) measurements. The morphology and size of the particles were controlled by solution acidity. The BET results confirmed that the materials are well crystallized and mesoporous in nature. The nanocrystalline powder was used to prepare thick films by screen printing on alumina substrate for the investigation of gas sensing properties. The gas response measurements revealed that the samples acidified using 10 M H2SO4 exhibits highest response of 91% towards NOX at optimum temperature of 200 °C for 100 ppm, and it also exhibits 35% response at room temperature.

Green synthesis of colloidal copper oxide nanoparticles using Carica papaya and its application in photocatalytic dye degradation

NASA Astrophysics Data System (ADS)

Sankar, Renu; Manikandan, Perumal; Malarvizhi, Viswanathan; Fathima, Tajudeennasrin; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

2014-03-01

Copper oxide (CuO) nanoparticles were synthesized by treating 5 mM cupric sulphate with Carica papaya leaves extract. The kinetics of the reaction was studied using UV-visible spectrophotometry. An intense surface Plasmon resonance between 250-300 nm in the UV-vis spectrum clearly reveals the formation of copper oxide nanoparticles. The results of scanning electron microscopy (SEM) and dynamic light scattering (DLS) exhibited that the green synthesized copper oxide nanoparticles are rod in shape and having a mean particle size of 140 nm, further negative zeta potential disclose its stability at -28.9 mV. The Fourier-transform infrared (FTIR) spectroscopy results examined the occurrence of bioactive functional groups required for the reduction of copper ions. X-ray diffraction (XRD) spectra confirmed the copper oxide nanoparticles crystalline nature. Furthermore, colloidal copper oxide nanoparticles effectively degrade the Coomassie brilliant blue R-250 dye beneath the sunlight.

A facile growth mechanism, structural, optical, dielectric and electrical properties of ZnSe nanosphere via hydrothermal process

NASA Astrophysics Data System (ADS)

Javed, Qurat-Ul-Ain; Baqi, Sabah; Abbas, Hussain; Bibi, Maryam

2017-02-01

Hydrothermal method was chosen as a convenient method to fabricate zinc selenide (ZnSe) nanoparticle materials. The prepared nanospheres were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), where its different properties were observed using UV-visible spectroscopy and LCR meter. It was found that the pure ZnSe nanoparticles have a Zinc blende structure with crystallite size 10.91 nm and in a spherical form with average diameter of 35 nm (before sonication) and 18 nm (after sonication) with wide band gap of 4.28 eV. It was observed that there is inverse relation of frequency with dielectric constant and dielectric loss while AC conductivity grows up by increasing frequency. Such nanostructures were determined to be effectively used in optoelectronic devices as UV detector and in those devices where high-dielectric constant materials are required.

Preparation of flower-like CuS by solvothermal method for photocatalytic, UV protection and EMI shielding applications

NASA Astrophysics Data System (ADS)

Hu, Xiao-Sai; Shen, Yong; Xu, Li-Hui; Wang, Li-Ming; Lu, Li-sha; Zhang, Ya-ting

2016-11-01

The flower-like CuS hierarchical structures were synthesized by solvothermal method. The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared(FTIR) spectroscopy, UV-vis optical absorption spectroscopy and thermogravimetric analysis (TGA). The results demonstrated that the as-prepared flower-like CuS with the diameter of 1-5 um was pure hexagonal phase CuS and had well-defined flower-like structures. (1) The as-prepared CuS was proved to possess high photocatalytic performance with band gap of 1.45 eV. The degradation rate of Methylene blue (MB) was up to, 98.26%, 100% after 30 min under UV and visible irradiation. (2)The UPF of cotton fabric treated with CuS reached up to 174 compared with the original untreated fabric with the UPF 20.62. (3) The electromagnetic interference shielding effectiveness (EMI SE) of CuS coating was up to 27-31 dB when the content of CuS increased to 28.6%wt in the frequency of 300 KHz-3 GHz. Furthermore, the influence of reaction conditions on the morphology of the as-prepared CuS was investigated systematically and the possible formation mechanism of the CuS hierarchical structure was also proposed.

Significantly enhanced photocatalytic activity of visible light responsive AgBr/Bi2Sn2O7 heterostructured composites

NASA Astrophysics Data System (ADS)

Hu, Chaohao; Zhuang, Jing; Zhong, Liansheng; Zhong, Yan; Wang, Dianhui; Zhou, Huaiying

2017-12-01

Heterostructured AgBr/Bi2Sn2O7 photocatalysts were synthesized successfully via the ultrasonic-assisted chemical precipitation method. XRD, FT-IR, FE-SEM, TEM, XPS, UV-vis-DRS and PL spectroscopy were used to characterize the phase structure, morphology, chemical composition, oxidation state, and optical properties of AgBr/Bi2Sn2O7 heterojunction. The photocatalytic activity of as-prepared catalysts was evaluated by the degradation of RhB under visible light irradiation. The obtained AgBr/Bi2Sn2O7 composite with the 1:1 molar ratio exhibited significantly enhanced photocatalytic performance. Further first-principles calculations indicated that the hybridization interaction between Ag and O atoms at AgBr/Bi2Sn2O7 interface is expected to be beneficial for enhancing the charge transfer and improving the photocatalytic activity of heterostructured composites.

Enhanced visible-light-driven photocatalytic H2-production activity of CdS-loaded TiO2 microspheres with exposed (001) facets

NASA Astrophysics Data System (ADS)

Gao, Bifen; Yuan, Xia; Lu, Penghui; Lin, Bizhou; Chen, Yilin

2015-12-01

CdS-loaded TiO2 microspheres with highly exposed (001) facets were prepared by hydrothermal treatment of a TiF4-HCl-H2O mixed solution followed by a chemical bath deposition of CdS onto TiO2 microspheres. The crystal structure, surficial micro-structure and photo-absorption property of the samples were characterized by XRD, FE-SEM, TEM and UV-vis diffuse reflectance spectroscopy, etc. The as-prepared samples exhibited superior visible-light-driven photocatalytic H2-production activity from lactic acid aqueous solution in comparison with CdS-sensitized TiO2 nanoparticles, whose surface was dominated by (101) facets. Photoelectrochemical measurement confirmed that (001) facet is beneficial for the transfer of photo-generated electron from CdS to TiO2 microsphere, which led to the unexpected high photocatalytic activity of CdS-loaded TiO2 microspheres.

Efficient red luminescence from organic-soluble Au25 clusters by ligand structure modification

NASA Astrophysics Data System (ADS)

Mathew, Ammu; Varghese, Elizabeth; Choudhury, Susobhan; Pal, Samir Kumar; Pradeep, T.

2015-08-01

An efficient method to enhance visible luminescence in a visibly non-luminescent organic-soluble 4-(tert butyl)benzyl mercaptan (SBB)-stabilized Au25 cluster has been developed. This method relies mainly on enhancing the surface charge density on the cluster by creating an additional shell of thiolate on the cluster surface, which enhances visible luminescence. The viability of this method has been demonstrated by imparting red luminescence to various ligand-protected quantum clusters (QCs), observable to the naked eye. The bright red luminescent material derived from Au25SBB18 clusters was characterized using UV-vis and luminescence spectroscopy, TEM, SEM/EDS, XPS, TG, ESI and MALDI mass spectrometry, which collectively proposed an uncommon molecular formula of Au29SBB24S, suggested to be due to different stapler motifs protecting the Au25 core. The critical role of temperature on the emergence of luminescence in QCs has been studied. The restoration of the surface ligand shell on the Au25 cluster and subsequent physicochemical modification to the cluster were probed by various mass spectral and spectroscopic techniques. Our results provide fundamental insights into the ligand characteristics determining luminescence in QCs.An efficient method to enhance visible luminescence in a visibly non-luminescent organic-soluble 4-(tert butyl)benzyl mercaptan (SBB)-stabilized Au25 cluster has been developed. This method relies mainly on enhancing the surface charge density on the cluster by creating an additional shell of thiolate on the cluster surface, which enhances visible luminescence. The viability of this method has been demonstrated by imparting red luminescence to various ligand-protected quantum clusters (QCs), observable to the naked eye. The bright red luminescent material derived from Au25SBB18 clusters was characterized using UV-vis and luminescence spectroscopy, TEM, SEM/EDS, XPS, TG, ESI and MALDI mass spectrometry, which collectively proposed an uncommon molecular formula of Au29SBB24S, suggested to be due to different stapler motifs protecting the Au25 core. The critical role of temperature on the emergence of luminescence in QCs has been studied. The restoration of the surface ligand shell on the Au25 cluster and subsequent physicochemical modification to the cluster were probed by various mass spectral and spectroscopic techniques. Our results provide fundamental insights into the ligand characteristics determining luminescence in QCs. Electronic supplementary information (ESI) available: Additional data on characterization of red luminescent Au29 QC and comparison with parent Au25SBB18 are given. See DOI: 10.1039/c5nr03457d

Acoustical, morphological and optical properties of oral rehydration salts (ORS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

George, Preetha Mary, E-mail: preethageoti@gmail.com, E-mail: jayakumars030@gmail.com; Divya, P.; Jayakumar, S., E-mail: preethageoti@gmail.com, E-mail: jayakumars030@gmail.com

Ultrasonic velocity, density and viscosity were measured in different concentrations of oral rehydration salts (ORS) at room temperature 303 k. From the experimental data other related thermodynamic parameters, viz adiabatic compressibility, intermolecular free length, acoustic impedence, relaxation time are calculated. The experimental data were discussed in the light of molecular interaction existing in the liquid mixtures. The results have been discussed in terms of solute-solvent interaction between the components. Structural characterization is important for development of new material. The morphology, structure and grain size of the samples are investigated by SEM. The optical properties of the sample have been studied usingmore » UV Visible spectroscopy.« less

Spinel NixZn1-xFe2O4 (0.0 ≤ x ≤ 1.0) nano-photocatalysts: Synthesis, characterization and photocatalytic degradation of methylene blue dye

NASA Astrophysics Data System (ADS)

Padmapriya, G.; Manikandan, A.; Krishnasamy, V.; Jaganathan, Saravana Kumar; Antony, S. Arul

2016-09-01

Spinel NixZn1-xFe2O4 (x = 0.0 to 1.0) nanoparticles were successfully synthesized by a simple microwave combustion method (MCM) using metal nitrates as raw materials and glycine as the fuel. The structural, morphological and opto-magnetic properties of the spinel NixZn1-xFe2O4 ferrites were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray (EDX) spectroscopy, high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED) pattern, UV-Visible diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and vibrating sample magnetometer (VSM). Powder XRD, and EDX analysis was confirmed the formation of pure phase of spinel ferrites. HR-SEM and HR-TEM analysis was confirmed the formation of sphere like-particle morphology of the samples with smaller agglomeration. VSM analysis clearly showed the superparamagnetic and ferromagnetic nature of the samples. The Ms value is 3.851 emu/g for undoped ZnFe2O4 sample and it increased with increase in Ni content. Photo-catalytic degradation (PCD) of methylene blue (MB) dye using the samples were carried out and observed good PCD results.

Green synthesis of silver nanoparticles using Cordia dichotoma fruit extract and its enhanced antibacterial, anti-biofilm and photo catalytic activity

NASA Astrophysics Data System (ADS)

Bharathi, Devaraj; Vasantharaj, Seerangaraj; Bhuvaneshwari, V.

2018-05-01

The present study describes the antibacterial, anti-biofilm and photo catalytic activity of silver nanoparticles synthesized using Cordia dichotoma fruits (Cd-AgNPs) for the first time. The phyto-synthesized Cd-AgNPs were characterized by UV-Visible spectroscopy, Field emission-scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), Energy dispersive x-ray spectrometer (EDX), Fourier transform infrared spectroscopy (FT-IR), and x-ray diffraction (XRD). FE-SEM and TEM observation showed that the average size of 2–60 nm with spherical shape of Cd-AgNPs and the presence of phyto-compounds which are responsible for capping and reduction were studied by FT-IR. XRD studies revealed the face-centered cubic structure of Cd-AgNPs. The synthesized Cd-AgNPs showed significant antibacterial activity against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, assayed using agar well diffusion method. Phyto-synthesized Cd-AgNPs exhibited more than 90% inhibition of biofilm activity formed by S. aureus and E. coli. Furthermore, photocatalytic degradation of crystal violet (CV) under UV light irradiation using Cd-AgNPs was performed. Synthesized Cd-AgNPs exhibited ∼85% degradation activity for CV. Collectively, our findings suggest that C.dichotoma is a green source for the eco-friendly synthesis of Cd-AgNPs, which further can be used as a novel biocidal agent against bacterial pathogens and a potent photo catalytic agent.

Preparation and photoelectrocatalytic performance of N-doped TiO2/NaY zeolite membrane composite electrode material.

PubMed

Cheng, Zhi-Lin; Han, Shuai

2016-01-01

A novel composite electrode material based on a N-doped TiO2-loaded NaY zeolite membrane (N-doped TiO2/NaY zeolite membrane) for photoelectrocatalysis was presented. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible (UV-vis) and X-ray photoelectron spectroscopy (XPS) characterization techniques were used to analyze the structure of the N-doped TiO2/NaY zeolite membrane. The XRD and SEM results verified that the N-doped TiO2 nanoparticles with the size of ca. 20 nm have been successfully loaded on the porous stainless steel-supported NaY zeolite membrane. The UV-vis result showed that the N-doped TiO2/NaY zeolite membrane exhibited a more obvious red-shift than that of N-TiO2 nanoparticles. The XPS characterization revealed that the doping of N element into TiO2 was successfully achieved. The photoelectrocatalysis performance of the N-doped TiO2/NaY zeolite membrane composite electrode material was evaluated by phenol removal and also the effects of reaction conditions on the catalytic performance were investigated. Owing to exhibiting an excellent catalytic activity and good recycling stability, the N-doped TiO2/NaY zeolite membrane composite electrode material was of promising application for photoelectrocatalysis in wastewater treatment.

Degradation of blue and red inks by Ag/AgCl photocatalyst under UV light irradiation

NASA Astrophysics Data System (ADS)

Daupor, Hasan; Chenea, Asmat

2017-08-01

Objective of this research, cubic Ag/AgCl photocatalysts with an average particle size of 500 nm has been successfully synthesized via a modified precipitation reaction between ZrCl4 and AgNO3. Method for analysis, the crystal structure of the product was characterized by X-ray powder diffraction (XRD). The morphology and composition were studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV-vis diffuse-reflection spectra (DRS) and so on. The result showed that the optical absorption spectrum exhibited strong absorption in the visible region around 500-600 nm due to surface plasmon resonance (SPR) of metallic silver nanoparticles. SEM micrographs showed that the obtained Ag/AgCl had cubic morphology and appeared on the porous surface as the cubic cage morphology. As a result, this porous surface also positively affected the photocatalytic reaction. The photocatalytic activity of the obtained product was evaluated by the photodegradation of blue and red ink solutions under UV light irradiation, and it was interestingly, discovered that AgCl could degrade 0.25% and 0.10% in 7 hours for blue and red inks solution respectively, Which were higher than of commercial AgCl. The result suggested that the morphology of Ag/AgCl strongly affected their photocatalytic activities. O2-, OH- reaction. radicals and Cl° atom are main species during photocatalytic reaction.

Size- and Shape-Dependent Antibacterial Studies of Silver Nanoparticles Synthesized by Wet Chemical Routes

PubMed Central

Raza, Muhammad Akram; Kanwal, Zakia; Rauf, Anum; Sabri, Anjum Nasim; Riaz, Saira; Naseem, Shahzad

2016-01-01

Silver nanoparticles (AgNPs) of different shapes and sizes were prepared by solution-based chemical reduction routes. Silver nitrate was used as a precursor, tri-sodium citrate (TSC) and sodium borohydride as reducing agents, while polyvinylpyrrolidone (PVP) was used as a stabilizing agent. The morphology, size, and structural properties of obtained nanoparticles were characterized by scanning electron microscopy (SEM), UV-visible spectroscopy (UV-VIS), and X-ray diffraction (XRD) techniques. Spherical AgNPs, as depicted by SEM, were found to have diameters in the range of 15 to 90 nm while lengths of the edges of the triangular particles were about 150 nm. The characteristic surface plasmon resonance (SPR) peaks of different spherical silver colloids occurring in the wavelength range of 397 to 504 nm, whereas triangular particles showed two peaks, first at 392 nm and second at 789 nm as measured by UV-VIS. The XRD spectra of the prepared samples indicated the face-centered cubic crystalline structure of metallic AgNPs. The in vitro antibacterial properties of all synthesized AgNPs against two types of Gram-negative bacteria, Pseudomonas aeruginosa and Escherichia coli were examined by Kirby–Bauer disk diffusion susceptibility method. It was noticed that the smallest-sized spherical AgNPs demonstrated a better antibacterial activity against both bacterial strains as compared to the triangular and larger spherical shaped AgNPs. PMID:28335201

Synthesis of silver nanoparticles using Solanum trilobatum fruits extract and its antibacterial, cytotoxic activity against human breast cancer cell line MCF 7

NASA Astrophysics Data System (ADS)

Ramar, Manikandan; Manikandan, Beulaja; Marimuthu, Prabhu Narayanan; Raman, Thiagarajan; Mahalingam, Anjugam; Subramanian, Palanisamy; Karthick, Saravanan; Munusamy, Arumugam

2015-04-01

In the present study, we have synthesized silver nanoparticles by a simple and eco-friendly method using unripe fruits of Solanum trilobatum. The aqueous silver ions when exposed to unripe fruits extract were reduced and stabilized over long time resulting in biosynthesis of surface functionalized silver nanoparticles. The bio-reduced silver nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX) and X-ray diffraction (XRD). These biologically synthesized silver nanoparticles were tested for its antibacterial activity against few human pathogenic bacteria including Gram-positive (Streptococcus mutans, Enterococcus faecalis) and Gram-negative (Escherichia coli, Klebsiella pneumoniae) bacteria. In addition, we also demonstrated anticancer activity of these nanoparticles in vitro against human breast cancer cell line (MCF 7) using MTT, nuclear morphology assay, Western blot and RT-PCR expression. These results taken together show the potential applications of biosynthesized silver nanoparticles using S. trilobatum fruits.

Fabrication of a temperature-responsive and recyclable MoS2 nanocatalyst through composting with poly (N-isopropylacrylamide)

NASA Astrophysics Data System (ADS)

Liu, Yan; Chen, Pengpeng; Nie, Wangyan; Zhou, Yifeng

2018-04-01

A temperature-responsive, recyclable nanocatalyst was fabricated by composting the exfoliated molybdenum disulfide (MoS2) nanosheets with poly (N-isopropylacry lamide) (PNIPAM). The structure and morphology of MoS2/PNIPAM nanocatalyst was fully characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Thermogravimetry analysis (TGA), Scanning electron microscope (SEM) and Transmission electron microscopy (TEM). The temperature-responsive properties of the MoS2/PNIPAM nanocatalyst were confirmed by Dynamic Light Scattering (DLS) and Ultraviolet-visible ((UV-vis)) absorption spectroscopy. The catalytic activities of the MoS2/PNIPAM nanocatalyst were studied using the reduction reaction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) as the model reaction. Results showed that the catalytic activity of the MoS2/PNIPAM nanocatalyst could be regulated by temperature. Furthermore, when the temperature went higher than the low critical solution temperature (LCST) of PNIPAM, the MoS2/PNIPAM nanocatalyst tended to aggregated to form bulk materials from homogeneous suspension.

Investigation of microstructural and optical properties of La0.8Ca0.2FeO3 nanostructure synthesized via gel combustion method

NASA Astrophysics Data System (ADS)

Naseem, Swaleha; Ali, S. Asad; Khan, Wasi; Khan, Shakeel

2018-05-01

Ca substituted LaFeO3 orthoferrite nanostructure perovskite has been synthesized by gel combustion method using citric acid as a fuel. The structural and optical properties were investigated by various tools. The structural analysis through Rietveld refinement of the XRD data revealed single phase of orthorhombic structure in R-3c space group of the sample without presence of any other impurity phase. Scanning electron microscopy (SEM) image exhibits non-uniform distribution of the nanoparticles in agglomerated form. The purity of the sample and stoichiometric ratio of the elements were established through energy dispersive x-ray spectroscopy (EDS). FTIR spectroscopy measurement predicts the presence of various band relation of the chemical species of Ca with LaFeO3. Optical properties were explored through UV-visible absorption spectroscopy that showed absorption edge at 347 nm and energy band gap was estimated as 3.47eV using Tauc's relation.

Synthesis of nano-titanium dioxide by sol-gel route

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaler, Vandana, E-mail: vandana.kaler@gmail.com; Duchaniya, R. K.; Pandel, U.

Nanosized titanium dioxide powder was synthesised via sol-gel route by hydrolysis of titanium tetraisopropoxide with ethanol and water mixture in high acidic medium. The synthesized nanopowder was further characterized by X-ray Diffraction, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and Ultraviolet Visible Spectroscopy in order to determine size, morphology and crystalline structure of the material. The synthesis of nano-TiO{sub 2} powder in anatase phase was realized by XRD. The optical studies of nano-TiO{sub 2} powder was carried out by UV-Vis spectroscopy and band gap was calculated as 3.5eV, The SEM results with EDAX confirmed that prepared nano-TiO{sub 2} particles weremore » in nanometer range with irregular morphology. The FTIR analysis showed that only desired functional groups were present in sample. These nano-TiO{sub 2} particles have applications in solar cells, chemical sensors and paints, which are thrust areas these days.« less

Green in-situ synthesized silver nanoparticles embedded in bacterial cellulose nanopaper as a bionanocomposite plasmonic sensor.

PubMed

Pourreza, Nahid; Golmohammadi, Hamed; Naghdi, Tina; Yousefi, Hossein

2015-12-15

Herein, we introduce a new strategy for green, in-situ generation of silver nanoparticles using flexible and transparent bacterial cellulose nanopapers. In this method, adsorbed silver ions on bacterial cellulose nanopaper are reduced by the hydroxyl groups of cellulose nanofibers, acting as the reducing agent producing a bionanocomposite "embedded silver nanoparticles in transparent nanopaper" (ESNPs). The fabricated ESNPs were investigated and characterized by field emission scanning electron microscopy (FE-SEM), UV-visible spectroscopy (UV-vis), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and energy-dispersive X-ray spectroscopy (EDX). The important parameters affecting the ESNPs were optimized during the fabrication of specimens. The resulting ESNPs were used as a novel and sensitive probe for the optical sensing of cyanide ion (CN(-)) and 2-mercaptobenzothiazole (MBT) in water samples with satisfactory results. The change in surface plasmon resonance absorption intensity of ESNPs was linearly proportional to the concentration in the range of 0.2-2.5 µg mL(-1) and 2-110 µg mL(-1) with a detection limit of 0.012 µg mL(-1) and 1.37 µg mL(-1) for CN(-) and MBT, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Au nanoparticle arrays produced by Pulsed Laser Deposition for Surface Enhanced Raman Spectroscopy

NASA Astrophysics Data System (ADS)

Agarwal, N. R.; Neri, F.; Trusso, S.; Lucotti, A.; Ossi, P. M.

2012-09-01

Using UV pulses from KrF excimer laser, Au targets were ablated in varying pressures of argon to deposit Au nanoparticle (NP) arrays. The morphology of these films from island structures to isolated NPs, observed by SEM and TEM, depends on the gas pressure (10-100 Pa) and pulse number keeping other deposition parameters constant. By fast imaging of the plasma with an iCCD camera at different time delays with respect to the arrival of the laser pulse, we study the plasma propagation regime and we measured its initial velocity. These data and the measured average ablated mass per pulse were introduced to the mixed propagation model to calculate the average asymptotic size of clusters grown in the plume which were compared with NP sizes from TEM measurements. UV-visible Spectroscopy revealed changes of surface plasmon resonance with respect to NP size and spatial density and distribution on the surface. Suitable wavelength to excite the localized surface plasmon was chosen to detect ultra-low concentrations of Rhodamine and Apomorphine as an application to biomedical sensors, using Surface Enhanced Raman Spectroscopy (SERS). A comparison of SERS spectra taken under identical conditions from commercial substrates and from PLD substrates show that the latter have superior performances.

Visible-light-responsive photocatalysts toward water oxidation based on NiTi-layered double hydroxide/reduced graphene oxide composite materials.

PubMed

Li, Bei; Zhao, Yufei; Zhang, Shitong; Gao, Wa; Wei, Min

2013-10-23

A visible-light responsive photocatalyst was fabricated by anchoring NiTi-layered double hydroxide (NiTi-LDH) nanosheets to the surface of reduced graphene oxide sheets (RGO) via an in situ growth method; the resulting NiTi-LDH/RGO composite displays excellent photocatalytic activity toward water splitting into oxygen with a rate of 1.968 mmol g(-1) h(-1) and a quantum efficiency as high as 61.2% at 500 nm, which is among the most effective visible-light photocatalysts. XRD patterns and SEM images indicate that the NiTi-LDH nanosheets (diameter: 100-200 nm) are highly dispersed on the surface of RGO. UV-vis absorption spectroscopy exhibits that the introduction of RGO enhances the visible-light absorption range of photocatalysts, which is further verified by the largely decreased band gap (∼1.78 eV) studied by cyclic voltammetry measurements. Moreover, photoluminescence (PL) measurements indicate a more efficient separation of electron-hole pairs; electron spin resonance (ESR) and Raman scattering spectroscopy confirm the electrons transfer from NiTi-LDH nanosheets to RGO, accounting for the largely enhanced carrier mobility and the resulting photocatalytic activity in comparison with pristine NiTi-LDH material. Therefore, this work demonstrates a facile approach for the fabrication of visible-light responsive NiTi-LDH/RGO composite photocatalysts, which can be used as a promising candidate in solar energy conversion and environmental science.

Biomimetic synthesis of selenium nanoparticles by Pseudomonas aeruginosa ATCC 27853: An approach for conversion of selenite.

PubMed

Kora, Aruna Jyothi; Rastogi, Lori

2016-10-01

A facile and green method for the reduction of selenite was developed using a Gram-negative bacterial strain Pseudomonas aeruginosa, under aerobic conditions. During the process of bacterial conversion, the elemental selenium nanoparticles were produced. These nanoparticles were systematically characterized using various analytical techniques including UV-visible spectroscopy, XRD, Raman spectroscopy, SEM, DLS, TEM and FTIR spectroscopy techniques. The generation of selenium nanoparticles was confirmed from the appearance of red colour in the culture broth and broad absorption peaks in the UV-vis. The synthesized nanoparticles were spherical, polydisperse, ranged from 47 to 165 nm and the average particle size was about 95.9 nm. The selected-area electron diffraction, XRD patterns; and Raman spectroscopy established the amorphous nature of the fabricated nanoparticles. The IR data demonstrated the bacterial protein mediated selenite reduction and capping of the produced nanoparticles. The selenium removal was assessed at different selenite concentrations using ICP-OES and the results showed that the tested bacterial strain exhibited significant selenite reduction activity. The results demonstrate the possible application of P. aeruginosa for bioremediation of waters polluted with toxic and soluble selenite. Moreover, the potential metal reduction capability of the bacterial strain can function as green method for aerobic generation of selenium nanospheres. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preparation of poly-o-phenylenediamine/TiO 2/fly-ash cenospheres and its photo-degradation property on antibiotics

NASA Astrophysics Data System (ADS)

Huo, Pengwei; Yan, Yongsheng; Li, Songtian; Li, Huaming; Huang, Weihong

2010-03-01

A series of poly-o-phenylenediamine/TiO 2/fly-ash cenospheres(POPD/TiO 2/fly-ash cenospheres) composites have been prepared from o-phenylenediamine and TiO 2/fly-ash cenospheres under various polymerization conditions. The properties of the samples were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), specific surface area (BET), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and UV-vis diffuse reflectance spectrum (UV-vis DRS). Photocatalytic activity was studied by degradation of antibiotics waste water under visible light. The results indicate that the photo-induced method is viable for preparing modified photocatalysts, and the modified photocatalysts have good absorption in visible light range. The photocatalysts of POPD/TiO 2/fly-ash cenospheres which have good performance are prepared at pH 3 and 4, and the polymerized time around 40 min. When the photocatalysts are prepared under the conditions of pH 3 and polymerized time 40 min, the degradation rate of roxithromycin waste water could reach near 60%, and it indicates that the way of POPD modified TiO 2/fly-ash cenospheres to degrade the antibiotics waste water is viable.

Preparation and photocatalytic activity of nonmetal Co-doped titanium dioxide photocatalyst

NASA Astrophysics Data System (ADS)

Sun, Xiaogang; Xing, Jun; Qiu, Jingping

2016-06-01

A series of boron and sulfur co-doped titanium dioxide (TiO2) photocatalysts were prepared by a sol-gel method using boric acid, thiourea and tetrabutyl titanate [Ti(OC4H9)4] as precursors. The photoabsorbance of as-prepared photocatalysts was measured by UV-Vis diffuse reflectance spectroscopy (DRS), and its microstructure was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and N2 adsorption-desorption measurements. The prepared photocatalysts consisted of the anatase phase mainly in the form of spherical particles. The photocatalytic performance was studied by photodegradation of methyl blue (MB) in water under UV and visible light irradiation. The calcination temperature and the codoping content influenced the photoactivity. The synergistic effect of boron and sulfur co-doping played an important role in improving the photocatalytic activity. In addition, the possibility of cyclic usage of codoped TiO2 was also confirmed, the photocatalytic activity of TiO2 remained above 91% of that of the fresh sample after being used four times. It was shown that the co-doped TiO2 could be activated by visible light and could thus be potentially applied for the treatment of water contaminated by organic pollutants.

Rapid photo-degradation of 2-chlorophenol under visible light irradiation using cobalt oxide-loaded TiO2/reduced graphene oxide nanocomposite from aqueous media.

PubMed

Sharma, Ajit; Lee, Byeong-Kyu

2016-01-01

The photocatalytic removal of 2-chlorophenol (2-CP) from water environment was investigated by TiO2-RGO-CoO. Cobalt oxide-loaded TiO2 (TiO2-CoO) supported with reduced graphene oxide (RGO) was synthesized using a sol-gel method and then annealed at 500 °C for 5 min. The material characteristics were analyzed by UV-Vis analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Incorporation of cobalt oxide and RGO into the TiO2 system (TiO2-RGO-CoO) lowered the band gap energy to 2.83 eV, which greatly enhanced the visible light absorption. The TiO2-RGO-CoO photocatalyst showed complete removal of 20 mg/L 2-CP within 8 h with the addition of 0.01% H2O2 under 100 W visible light irradiation. The photo-degradation efficiency of 2-CP (10 mg/L) was 35.2, 48.9, 58.9 and 98.2% for TiO2, TiO2-RGO, TiO2-CoO and TiO2-RGO-CoO, respectively, in the presence of visible light irradiation at solution pH of 6.0. The TiO2-RGO-CoO photocatalyst retained its high removal efficiency even after five photocatalytic cycles. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Use of UV-Visible Reflectance Spectroscopy as an Objective Tool to Evaluate Pearl Quality

PubMed Central

Agatonovic-Kustrin, Snezana; Morton, David W.

2012-01-01

Assessing the quality of pearls involves the use of various tools and methods, which are mainly visual and often quite subjective. Pearls are normally classified by origin and are then graded by luster, nacre thickness, surface quality, size, color and shape. The aim of this study was to investigate the capacity of Artificial Neural Networks (ANNs) to classify and estimate the quality of 27 different pearls from their UV-Visible spectra. Due to the opaque nature of pearls, spectroscopy measurements were performed using the Diffuse Reflectance UV-Visible spectroscopy technique. The spectra were acquired at two different locations on each pearl sample in order to assess surface homogeneity. The spectral data (inputs) were smoothed to reduce the noise, fed into ANNs and correlated to the pearl’s quality/grading criteria (outputs). The developed ANNs were successful in predicting pearl type, mollusk growing species, possible luster and color enhancing, donor condition/type, recipient/host color, donor color, pearl luster, pearl color, origin. The results of this study shows that the developed UV-Vis spectroscopy-ANN method could be used as a more objective method of assessing pearl quality (grading) and may become a valuable tool for the pearl grading industry. PMID:22851919

Novel band gap-tunable K-Na co-doped graphitic carbon nitride prepared by molten salt method

NASA Astrophysics Data System (ADS)

Zhao, Jiannan; Ma, Lin; Wang, Haoying; Zhao, Yanfeng; Zhang, Jian; Hu, Shaozheng

2015-03-01

Novel band gap-tunable K-Na co-doped graphitic carbon nitride was prepared by molten salt method using melamine, KCl, and NaCl as precursor. X-ray diffraction (XRD), N2 adsorption, Scanning electron microscope (SEM), UV-vis spectroscopy, Photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared catalysts. The CB and VB potentials of graphitic carbon nitride could be tuned from -1.09 and +1.55 eV to -0.29 and +2.25 eV by controlling the weight ratio of eutectic salts to melamine. Besides, ions doping inhibited the crystal growth of graphitic carbon nitride, enhanced the surface area, and increased the separation rate of photogenerated electrons and holes. The visible-light-driven Rhodamine B (RhB) photodegradation and mineralization performances were significantly improved after K-Na co-doping.

Tungsten-Doped TiO2 Nanolayers with Improved CO2 Gas Sensing Properties for Environmental Applications

NASA Astrophysics Data System (ADS)

Saberi, Maliheh; Ashkarran, Ali Akbar

Tungsten-doped TiO2 gas sensors were successfully synthesized using sol-gel process and spin coating technique. The fabricated sensor was characterized by field emission scanning electron microscopy (FE-SEM), ultraviolet visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), X-Ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Gas sensing properties of pristine and tungsten-doped TiO2 nanolayers (NLs) were probed by detection of CO2 gas. A series of experiments were conducted in order to find the optimum operating temperature of the prepared sensors and also the optimum value of tungsten concentration in TiO2 matrix. It was found that introducing tungsten into the TiO2 matrix enhanced the gas sensing performance. The maximum response was found to be (1.37) for 0.001g tungsten-doped TiO2 NLs at 200∘C as an optimum operating temperature.

Adsorption Studies of Gadolinium ion on Graphitic Carbon Nitride

NASA Astrophysics Data System (ADS)

Kuila, S. K.; Kundu, T. K.

2018-03-01

Bulk graphitic carbon nitride (g-C3N4) is synthesized by thermal decomposition of urea and used as an adsorbent for gadolinium ion (Gd3+) from aqueous solution. Adsorption capacity of g-C3N4 is found to be influenced by initial Gd3+ concentration, solution pH and contact time. Adsorbed Gd3+is separated from g-C3N4 by ultracentrifuge. Initial and Gd ion accumulated g-C3N4 adsorbent are characterized by X-ray diffraction technique (XRD) for phase identification, UV-visible and Fourier transform infrared (FTIR) spectroscopy for adsorption characteristics and optical property, scanning electron microscopy (SEM) for morphological behaviour along with energy dispersive X-ray spectroscopy (EDS) for elemental study. HNO3(0.1M), NaOH (0.1M) and de-ionized water are used for desorption and around 97% quantitative recovery of Gd ion is observed.

UV-Visible and Infrared Methods for Investigating Lipid-Rhodopsin Membrane Interactions

PubMed Central

Brown, Michael F.

2017-01-01

Summary Experimental UV-visible and Fourier transform infrared (FTIR) spectroscopic methods are described for characterizing lipid-protein interactions for the example of rhodopsin in a membrane bilayer environment. The combined use of FTIR and UV-visible difference spectroscopy monitors the structural and functional changes during rhodopsin activation. Such studies investigate how membrane lipids stabilize the various rhodopsin photoproducts, analogous to mutating the protein. Interpretation of the results entails a non-specific flexible surface model for explaining the role of membrane lipid-protein interactions in biological functions. PMID:22976026

Physicochemcial characteristic of CdS-anchored porous WS2 hybrid in the photocatalytic degradation of crystal violet under UV and visible light irradiation

NASA Astrophysics Data System (ADS)

Vattikuti, S. V. Prabhakar; Ngo, Ich-Long; Byon, Chan

2016-11-01

In this work, we report the synthesis of CdS-incorporated porous WS2 by a simple hydrothermal method. The structural, morphological, and optical properties of the samples were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), high resolution X-ray photoelectron spectroscopy (XPS) and UV-visible spectrometry. The photocatalytic activities were established for degradation of crystal violet (CV) under UV and visible light irradiation. The CdS-incorporated porous WS2 hybrid demonstrated high photocatalytic activity for degradation of CV pollutant compared to pure CdS nanoparticles and porous WS2 sheets. This result implies that the CdS-incorporated porous WS2 promoted more electron-hole pair transformation under UV and visible light irradiation. This significant enhancement of photocatalytic efficiency of CdS-incorporated porous WS2 photocatalyst under visible light can be ascribed to the presence of CdS nanospheres on the meshed-like WS2 sheets which potentially improves absorption in the visible range enabled by surface plasmon resonance effect of CdS nanospheres. The photostability and reusability of the CdS-porous WS2 were examined through recycling experiments.

Photocatalytic Activity of Vanadium-Substituted ETS-10

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nash,M.; Rykov, S.; Lobo, R.

2007-01-01

Various amounts of vanadium have been isomorphously substituted for titanium in ETS-10, creating samples with V/(V+Ti) ratios of 0.13, 0.33, 0.43, and 1.00 and characterized experimentally using Raman, near-edge X-ray absorption fine structure (NEXAFS), X-ray powder diffraction, N{sub 2} adsorption, scanning electron microscopy (SEM), UV/vis spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Raman spectra reveal a disordered chain structure that contains different V-O bonds along with the presence of a V-O-Ti peak. The UV/vis spectra of the vanadium samples have three new absorption features in the visible region at 450, 594, and 850 nm, suggesting both V{sup 4+}more » and V{sup 5+} are present in the samples. NEXAFS results confirm the presence of both V{sup 5+} and V{sup 4+} in the vanadium samples, with a fraction of V{sup 4+} within the range of 0.2-0.4. The addition of vanadium lowers the band gap energy of ETS-10 from 4.32 eV to a minimum of 3.58 eV for the 0.43ETVS-10 sample. Studies of the photocatalytic polymerization of ethylene show that the 594 nm transition has no photocatalytic activity. The visible transition around 450 nm in the vanadium-incorporated samples is photocatalytically active, and the lower-concentration vanadium samples have higher photocatalytic activity than that of ETS-10 and AM-6, the all-vanadium analogue of ETS-10.« less

Single crystal growth by gel technique and characterization of lithium hydrogen tartrate

NASA Astrophysics Data System (ADS)

Ahmad, Nazir; Ahmad, M. M.; Kotru, P. N.

2015-02-01

Single crystal growth of lithium hydrogen tartrate by gel encapsulation technique is reported. Dependence of crystal count on gel density, gel pH, reactant concentration and temperature are studied and the optimum conditions for these crystals are worked out. The stoichiometric composition of the grown crystals is determined using EDAX/AES and CH analysis. The grown crystals are characterized by X-ray diffraction, FTIR and Uv-Visible spectroscopy. It is established that crystal falls under orthorhombic system and space group P222 with the cell parameters as: a=10.971 Å, b=13.125 Å and c=5.101 Å; α=90.5o, β=γ=90°. The morphology of the crystals as revealed by SEM is illustrated. Crystallite size, micro strain, dislocation density and distortion parameters are calculated from the powder XRD results of the crystal. UV-vis spectroscopy shows indirect allowed transition with an optical band gap of 4.83 eV. The crystals are also shown to have high transmittance in the entire visible region. Dependence of dielectric constant, dielectric loss and conductivity on frequency of the applied ac field is analyzed. The frequency-dependent real part of the complex ac conductivity is found to follow the universal dielectric response: σac (ω) ωs. The trend in the variation of frequency exponent with frequency corroborates the fact that correlated barrier hopping is the dominant charge-transport mechanism in the present system.

Silk fibroin/gold nanocrystals: a new example of biopolymer-based nanocomposites

NASA Astrophysics Data System (ADS)

Noinville, S.; Garnier, A.; Courty, A.

2017-05-01

The dispersion of nanoparticles in ordered polymer nanostructures can provide control over particle location and orientation, and pave the way for tailored nanomaterials that have enhanced mechanical, electrical, or optical properties. Here we used silk fibroin, a natural biopolymer, to embed gold nanocrystals (NCs), so as to obtain well-ordered structures such as nanowires and self-assembled triangular nanocomposites. Monodisperse gold NCs synthesized in organic media are mixed to silk fibroin and the obtained nanocomposites are characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and Infrared spectroscopy. The optical properties study of gold NCs and silk-gold nanocomposites shows that the Surface Plasmon band is blue shifted compared to gold NCs. The size and shape of NCs gold superlattices can be well controlled by the presence of silk fibroin giving nanowires and also self-assembled triangular nanocomposites as characterized by TEM, FE-SEM and AFM. The strong interaction between gold NCs and silk fibroin is also revealed by the conformation change of silk protein in presence of gold NCs, as shown by FTIR analysis. The formation of such ordered nanocomposites (gold NCs/silk fibroin) will provide new nanoplasmonic devices.

Preparation and characterization of cross-linked poly (vinyl alcohol)-graphene oxide nanocomposites as an interlayer for Schottky barrier diodes

NASA Astrophysics Data System (ADS)

Badrinezhad, Lida; Bilkan, Çigdem; Azizian-Kalandaragh, Yashar; Nematollahzadeh, Ali; Orak, Ikram; Altindal, Şemsettin

2018-01-01

Cross-linked polyvinyl alcohol (PVA) graphene oxide (GO) nanocomposites were prepared by simple solution-mixing route and characterized by Raman, UV-visible and fourier transform infrared (FT-IR) spectroscopy analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The XRD pattern and SEM analysis showed significant changes in the nanocomposite structures, and the FT-IR spectroscopy results confirmed the chemical interaction between the GO filler and the PVA matrix. After these morphological characterizations, PVA-GO-based diodes were fabricated and their electrical properties were characterized using current-voltage (I-V) and impedance-voltage-frequency (Z-V-f) measurements at room temperature. Semilogarithmic I-V characteristics of diode showed a good rectifier behavior. The values of C and G/ω increased with decreasing frequency due to the surface/interface states (Nss) which depend on the relaxation time and the frequency of the signal. The voltage, dependent profiles of Nss and series resistance (Rs) were obtained from the methods of high-low frequency capacitance and Nicollian and Brews, respectively. The obtained values of Nss and Rs were attributed to the use of cross-linked PVA-GO interlayer at the Au/n-Si interface.

Effect of isovalent dopants on photodegradation ability of ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Khaparde, Rohini; Acharya, Smita

2016-06-01

Isovalent (Mn, Cd, Cu, Co)-doped-ZnS nanoparticles having size vary in between 2 to 5 nm are synthesized by co-precipitation route. Their photocatalytic activity for decoloration of Cango Red and Malachite Green dyes is tested in visible radiation under natural conditions. Structural and morphological features of the samples are investigated by X-ray diffraction, Raman spectroscopy, Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and UVsbnd Vis spectrometer. Single phase zinc blende structure of as-synthesized undoped and doped-ZnS is confirmed by XRD and revealed by Rietveld fitting. SEM and TEM images show ultrafine nanoparticles having size in the range of 2 to 5 nm. UV-Vis absorption spectra exhibit blue shift in absorption edge of undoped and doped ZnS as compared to bulk counterpart. The photocatalytic activity as a function of dopant concentration and irradiation time is systematically studied. The rate of de-coloration of dyes is detected by UVsbnd Vis absorption spectroscopy and organic dye mineralization is confirmed by table of carbon (TOC) study. The photocatalytic activity of Mn-doped ZnS is highest amongst all dopants; however Co as a dopant is found to reduce photocatalytic activity than pure ZnS.

Self-Organized TiO₂-MnO₂ Nanotube Arrays for Efficient Photocatalytic Degradation of Toluene.

PubMed

Nevárez-Martínez, María C; Kobylański, Marek P; Mazierski, Paweł; Wółkiewicz, Jolanta; Trykowski, Grzegorz; Malankowska, Anna; Kozak, Magda; Espinoza-Montero, Patricio J; Zaleska-Medynska, Adriana

2017-03-31

Vertically oriented, self-organized TiO₂-MnO₂ nanotube arrays were successfully obtained by one-step anodic oxidation of Ti-Mn alloys in an ethylene glycol-based electrolyte. The as-prepared samples were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), UV-Vis absorption, photoluminescence spectroscopy, X-ray diffraction (XRD), and micro-Raman spectroscopy. The effect of the applied potential (30-50 V), manganese content in the alloy (5-15 wt. %) and water content in the electrolyte (2-10 vol. %) on the morphology and photocatalytic properties was investigated for the first time. The photoactivity was assessed in the toluene removal reaction under visible light, using low-powered LEDs as an irradiation source (λ max = 465 nm). Morphology analysis showed that samples consisted of auto-aligned nanotubes over the surface of the alloy, their dimensions were: diameter = 76-118 nm, length = 1.0-3.4 μm and wall thickness = 8-11 nm. It was found that the increase in the applied potential led to increase the dimensions while the increase in the content of manganese in the alloy brought to shorter nanotubes. Notably, all samples were photoactive under the influence of visible light and the highest degradation achieved after 60 min of irradiation was 43%. The excitation mechanism of TiO₂-MnO₂ NTs under visible light was presented, pointing out the importance of MnO₂ species for the generation of e - and h⁺.

Measurements of the rate constant of HOsub2 + NOsub2 + Nsub2 --> HOsub2NOsub2 + Nsub2 using near-infrared wavelength-modulation spectroscopy and UV-visible absorption spectroscopy

NASA Technical Reports Server (NTRS)

Christensen, L. E.; Okumura, M.; Sander, S. P.; Friedl, R. R.; Miller, C. E.; Sloan, J. J.

2004-01-01

Rate coefficients for the reaction HO(sub 2)+ NO(sub 2) + N(sub 2) --> HO(sub 2)NO(sub 2) + N(sub 2) (reaction 1) were measured using simultaneous near-IR and UV spectroscopy from 220 to 298 K and from 45 to 200 Torr.

Solvothermal fabrication of activated semi-coke supported TiO2-rGO nanocomposite photocatalysts and application for NO removal under visible light

NASA Astrophysics Data System (ADS)

Yang, Weiwei; Li, Chunhu; Wang, Liang; Sun, ShengNan; Yan, Xin

2015-10-01

The photocatalysts of activated semi-coke supported TiO2-rGO nanocomposite (TiO2-rGO/ASC) with different contents of reduced graphene oxide were fabricated by one-step solvothermal method for NO removal under visible light irradiation. It was confirmed that 8% content of reduced graphene oxide presented the best NO photooxidation performance under visible light irradiation at 70 °C with 350-400 mg/m3 NO,5% O2 and 5% relative humidity. The reasons for improved activity were discussed, alloyed with the mechanism of producing CO. Detailed structural information of TiO2-rGO/ASC photocatalysts was characterized by scanning electron microscope (SEM), energy dispersive X-ray Spectroscopy (EDX), X-ray diffraction analysis (XRD), UV-Vis diffuse reflectance spectra (UV-Vis DRS) and photoluminescence (PL), which indicated that the introduction of rGO was responsible for well dispersion, smaller crystalline size, red shift of absorption band and suppressing quick photo-induced charges recombination of TiO2-rGO/ASC photocatalysts. Optimization of operational parameters with 70 °C, 8% O2 and 8% relative humidity were also obtained. Deactivation of TiO2-rGO/ASC photocatalysts for NO removal was investigated by Fourier-transform infrared (FTIR) analysis. Regeneration experiments showed that thermal vapor regeneration would be optimal method owing to excellent regenerative capacity and inexpensive procedure.

Advances in quantitative UV-visible spectroscopy for clinical and pre-clinical application in cancer.

PubMed

Brown, J Quincy; Vishwanath, Karthik; Palmer, Gregory M; Ramanujam, Nirmala

2009-02-01

Methods of optical spectroscopy that provide quantitative, physically or physiologically meaningful measures of tissue properties are an attractive tool for the study, diagnosis, prognosis, and treatment of various cancers. Recent development of methodologies to convert measured reflectance and fluorescence spectra from tissue to cancer-relevant parameters such as vascular volume, oxygenation, extracellular matrix extent, metabolic redox states, and cellular proliferation have significantly advanced the field of tissue optical spectroscopy. The number of publications reporting quantitative tissue spectroscopy results in the UV-visible wavelength range has increased sharply in the past three years, and includes new and emerging studies that correlate optically measured parameters with independent measures such as immunohistochemistry, which should aid in increased clinical acceptance of these technologies.

Structural and Optical Behaviour of Ar+ Implanted Polycarbonate

NASA Astrophysics Data System (ADS)

Shekhawat, Nidhi; Aggarwal, Sanjeev; Sharma, Annu; Deshpande, S. K.; Nair, K. G. M.

2011-07-01

Effects of 130 keV Ar+ ion implantation on the structural and optical properties of polycarbonate specimens have been studied using Raman, UV-Visible spectroscopy and glancing angle X-ray diffraction techniques. Formation of disordered carbonaceous network in the implanted layers has been observed using Raman and UV-Visible spectroscopy. A sharp decline in band gap values (4.1 eV to 0.63 eV) with increase in implantation dose has been observed. This decrease in optical band gap has been correlated with the formation of disordered structures in the implanted layers of polycarbonate.

Crystal Structure, Magnetic and Optical Properties of Mn-Doped BiFeO₃ by Hydrothermal Synthesis.

PubMed

Zhang, Ning; Wei, Qinhua; Qin, Laishun; Chen, Da; Chen, Zhi; Niu, Feng; Wang, Jiangying; Huanag, Yuexiang

2017-01-01

In this paper, Mn doped BiFeO₃ were firstly synthesized by hydrothermal process. The influence of Mn doping on structural, optical and magnetic properties of BiFeO₃ was studied. The different amounts of Mn doping in BiFeO₃ were characterized by X-ray diffraction, Scanning Electron Microscope, Energy Dispersive X-ray Spectroscope, UV-Vis diffuse reflectance spectroscopy and magnetic measurements. The X-ray diffraction (XRD) patterns confirmed the formation of pure phase rhombohedral structure in BiFe(1−x) Mn (x) O₃ (x = 0.01, 0.03, 0.05, 0.07) samples. The morphologies and chemical compositions of as-prepared samples could be observed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscope (EDS). A relative large saturated magnetization (Ms) of 0.53 emu/g for x = 0.07 sample was obtained at room temperature, which is considered to be Mn ions doping. UV-Vis diffuse reflectance spectroscopy showed strong absorption of light in the range of 200–1000 nm, indicating the optical band gap in the visible region for these samples. This implied that BiFe(1−x) Mn(x)O₃ may be a potential photocatalyst for utilizing solar energy.

UV-visible light-activated Ag-decorated, monodisperse TiO2 aggregates for treatment of the pharmaceutical oxytetracycline.

PubMed

Han, Changseok; Likodimos, Vlassis; Khan, Javed Ali; Nadagouda, Mallikarjuna N; Andersen, Joel; Falaras, Polycarpos; Rosales-Lombardi, Pablo; Dionysiou, Dionysios D

2014-10-01

Noble metal Ag-decorated, monodisperse TiO2 aggregates were successfully synthesized by an ionic strength-assisted, simple sol-gel method and were used for the photocatalytic degradation of the antibiotic oxytetracycline (OTC) under both UV and visible light (UV-visible light) irradiation. The synthesized samples were characterized by X-ray diffraction analysis (XRD); UV-vis diffuse reflectance spectroscopy; environmental scanning electron microscopy (ESEM); transmission electron microscopy (TEM); high-resolution TEM (HR-TEM); micro-Raman, energy-dispersive X-ray spectroscopy (EDS); and inductively coupled plasma optical emission spectrometry (ICP-OES). The results showed that the uniformity of TiO2 aggregates was finely tuned by the sol-gel method, and Ag was well decorated on the monodisperse TiO2 aggregates. The absorption of the samples in the visible light region increased with increasing Ag loading that was proportional to the amount of Ag precursor added in the solution over the tested concentration range. The Brunauer, Emmett, and Teller (The BET) surface area slightly decreased with increasing Ag loading on the TiO2 aggregates. Ag-decorated TiO2 samples demonstrated enhanced photocatalytic activity for the degradation of OTC under UV-visible light illumination compared to that of pure TiO2. The sample containing 1.9 wt% Ag showed the highest photocatalytic activity for the degradation of OTC under both UV-visible light and visible light illumination. During the experiments, the detected Ag leaching for the best TiO2-Ag photocatalyst was much lower than the National Secondary Drinking Water Regulation for Ag limit (0.1 mg L(-1)) issued by the US Environmental Protection Agency.

Inhibitory effect of xanthan gum and synergistic surfactant additives for mild steel corrosion in 1M HCl.

PubMed

Mobin, Mohammad; Rizvi, Marziya

2016-01-20

Natural polymer xanthan gum (XG) was investigated as eco friendly corrosion inhibitor for mild steel in 1M HCl at 30 °C, 40 °C, 50 °C and 60 °C, respectively. The inhibition studies were performed using gravimetric analysis, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), quantum chemical calculations, scanning electron microscopy (SEM), and UV-visible spectrophotometry. XG significantly reduces the corrosion rates of mild steel. The inhibition efficiency (IE) of the XG increased with increase in concentration, but decreased with temperature; the maximum IE of 74.24% was obtained at concentration of 1000 ppm at 30 °C. The inhibiting action of XG is synergistically enhanced on addition of very small amount of surfactants sodium dodecyl sulfate (SDS), cetyl pyridinium chloride (CPC) and Triton X-100 (TX). The effect of SDS is more pronounced than other surfactants. Potentiodynamic polarization studies confirm XG as a mixed type inhibitor. Results of weight loss measurements are in good agreement of the results of electrochemical measurements. The UV-visible spectroscopic results indicate the formation of complex between XG and Fe(2+) ions during corrosion reaction. Mechanism of inhibition was also investigated by calculating the thermodynamic and activation parameters like ΔG(0), Ea, ΔH and ΔS. The adsorption of inhibitor on mild steel surface obeys Langmuir adsorption isotherm. SEM micrographs show a clearly different morphology in presence of XG and XG-surfactant additives and confirmed the existence of an adsorbed protective film on the mild steel surface. Copyright © 2015 Elsevier Ltd. All rights reserved.

Design of binary SnO{sub 2}-CuO nanocomposite for efficient photocatalytic degradation of malachite green dye

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Aniket; Rout, Lipeeka; Achary, L. Satish Kumar

2016-04-13

Semiconductor mediated photocatalysis has got enormous consideration as it has shown immense potential in addressing the overall energy and environmental issues. To overcome the earlier drawbacks concerning quick charge recombination and limited visible-light absorption of semiconductor photocatalysts, numerous methods have been produced in the past couple of decades and the most broadly utilized one is to develop the photocatalytic heterojunctions. In our work, a series of SnO{sub 2}-CuO nanocomposites of different compositions were synthesized by a combustion method and have been investigated in detail by various characterization techniques, such as wide angle X-ray diffraction (XRD), UV-vis spectroscopy, transmission electron microscopymore » (TEM), and field emission scanning electron microscopy (FE-SEM). The results revealed that the crystal structure and optical properties of the nanocomposites were almost same for all the compositions. FE-SEM images showed that the shape of SnO{sub 2}-CuO was spherical in nature and the 1: 1 Sn/Cu sample had a well-proportioned morphology. The malachite green dye was used for the photocatalytic studies in a photoreactor and monitored with a UV-visible spectrometer for different composition ratio of metal (Sn: Cu) such as 1:1, 1:2, 2:1, 1:0.5 and 0.5:1. The 1:1 ratio nanocomposite showed excellent photocatalytic degradation of 96 % compared to pure SnO{sub 2} and CuO. The mechanism of degradation and charge separation ability of the nanocomposite are also explored using photocurrent measurement study.« less

UV / Visible / Near-Infrared Reflectance Models for the Rapid and Non-Destructive Prediction and Classification of Cotton Color and Physical Indices

USDA-ARS?s Scientific Manuscript database

High volume instrumentation (HVI), utilized in the cotton industry to determine the qualities and classifications of cotton fibers, is time consuming, and prone to day-to-day and location-to-location variations. UV / visible / NIR spectroscopy, a rapid and easy sampling technique, was investigated a...

Efficient photocatalytic degradation of organic pollutants by magnetically recoverable nitrogen-doped TiO2 nanocomposite photocatalysts under visible light irradiation.

PubMed

Hamzezadeh-Nakhjavani, Sahar; Tavakoli, Omid; Akhlaghi, Seyed Parham; Salehi, Zeinab; Esmailnejad-Ahranjani, Parvaneh; Arpanaei, Ayyoob

2015-12-01

Preparation of novel nanocomposite particles (NCPs) with high visible-light-driven photocatalytic activity and possessing recovery potential after advanced oxidation process (AOP) is much desired. In this study, pure anatase phase titania (TiO2) nanoparticles (NPs) as well as three types of NCPs including nitrogen-doped titania (TiO2-N), titania-coated magnetic silica (Fe3O4 cluster@SiO2@TiO2 (FST)), and a novel magnetically recoverable TiO2 nanocomposite photocatalyst containing nitrogen element (Fe3O4 cluster@SiO2@TiO2-N (FST-N)) were successfully synthesized via a sol-gel process. The photocatalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM) with an energy-dispersive X-ray (EDX) spectroscopy analysis, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and vibrating sample magnetometer (VSM). The photocatalytic activity of as-prepared samples was further investigated and compared with each other by degradation of phenol, as a model for the organic pollutants, in deionized (DI) water under visible light irradiation. The TiO2-N (55 ± 1.5%) and FST-N (46 ± 1.5%) samples exhibited efficient photocatalytic activity in terms of phenol degradation under visible light irradiation, while undoped samples were almost inactive under same operating conditions. Moreover, the effects of key operational parameters, the optimum sample calcination temperature, and reusability of FST-N NCPs were evaluated. Under optimum conditions (calcination temperature of 400 °C and near-neutral reaction medium), the obtained results revealed efficient degradation of phenol for FST-N NCPs under visible light irradiation (46 ± 1.5%), high yield magnetic separation and efficient reusability of FST-N NCPs (88.88% of its initial value) over 10 times reuse.

Structural phase analysis and photoluminescence properties of Mg-doped TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Ali, T.; Ashraf, M. Anas; Ali, S. Asad; Ahmed, Ateeq; Tripathi, P.

2018-05-01

In this paper, we report the synthesis, characterization and photoluminescence properties of Mg-doped TiO2 nanoparticles (NPs). The samples were synthesized by sol-gel method and characterized using the standard analytical techniques such as X-ray diffraction (XRD), Transmission electron microscope (TEM), Energy dispersive X-ray spectroscopy (EDX), UV-visible and photoluminescence spectroscopy. The powder XRD spectra revealed that the synthesized samples are pure and crystalline in nature and showing tetragonal anatase phase of TiO2 NPs. UV-visible spectrum illustrates that an absorption edge shifts toward the visible region. This study may provide a new insight for making the nanomaterials which can be used in photocatalytic applications.

One-step growth of nanosheet-assembled BiOCl/BiOBr microspheres for highly efficient visible photocatalytic performance

NASA Astrophysics Data System (ADS)

Zhang, Jinfeng; Lv, Jiali; Dai, Kai; Liang, Changhao; Liu, Qi

2018-02-01

In this work, we have developed a simple synthetic approach of nanosheet-assembled BiOCl/BiOBr microspheres by an ethylene glycol (EG)-assisted hydrothermal method. The crystalline form, morphology, chemical composition, optical performance and surface area of BiOCl/BiOBr microspheres were identified using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM (HRTEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy spectra (EDX), UV-vis diffuse reflectance spectroscopy (DRS) analysis, high resolution X-ray photoelectron spectra (XPS) and N2 adsorption-desorption isotherms. BiOCl/BiOBr microspheres were nanosheet-assembled particles, which possessed visible light absorption under LED light irridation. Additionally, the methylene blue (MB) photodegradation performance of different BiOCl/BiOBr microspheres irradiated under 410 nm LED light arrays were investigated, the results exhibited that as-prepared BiOCl/BiOBr products showed higher catalytic effiency than pure BiOCl or BiOBr. By optimizing the composition ration of the BiOCl and BiOBr, up to 93% degradation rate can be obtained in the 40%BiOCl/BiOBr microspheres. Finally, the photocatalytic mechanism of BiOCl/BiOBr microspheres had been proposed.

Facile Preparation of Nano-Bi₂MoO₆/Diatomite Composite for Enhancing Photocatalytic Performance under Visible Light Irradiation.

PubMed

Cai, Lu; Gong, Jiuyan; Liu, Jianshe; Zhang, Hailong; Song, Wendong; Ji, Lili

2018-02-09

In this work, a new nano-Bi₂MoO₆/diatomite composite photocatalyst was successfully synthesized by a facile solvothermal method. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV-vis diffuse reflection spectroscopy (DRS) were employed to investigate the morphology, crystal structure, and optical properties. It was shown that nanometer-scaled Bi₂MoO₆ crystals were well-deposited on the surface of Bi₂MoO₆/diatomite. The photocatalytic activity of the obtained samples was evaluated by the degradation of rhodamine B (RhB) under the visible light (λ > 420 nm) irradiation. Moreover, trapping experiments were performed to investigate the possible photocatalytic reaction mechanism. The results showed that the nano-Bi₂MoO₆/diatomite composite with the mass ratio of Bi₂MoO₆ to diatomaceous earth of 70% exhibited the highest activity, and the RhB degradation efficiency reached 97.6% within 60 min. The main active species were revealed to be h⁺ and•O 2- . As a photocatalytic reactor, its recycling performance showed a good stability and reusability. This new composite photocatalyst material holds great promise in the engineering field for the environmental remediation.

The effect of the solution flow rate on the properties of zinc oxide (ZnO) thin films deposited by ultrasonic spray

NASA Astrophysics Data System (ADS)

Attaf, A.; Benkhetta, Y.; Saidi, H.; Bouhdjar, A.; Bendjedidi, H.; Nouadji, M.; Lehraki, N.

2015-03-01

In this work, we used a system based on ultrasonic spray pyrolysis technique. By witch, we have deposited thin films of zinc oxide (ZnO) with the variation of solution flow rate from 50 ml / h to 150 ml / h, and set other parameters such as the concentration of the solution, the deposition time, substrate temperature and the nozzel -substrate distance. In order to study the influence of the solution flow rate on the properties of the films produced, we have several characterization techniques such as X-ray diffraction to determine the films structure, the scanning electron microscopy SEM for the morphology of the surfaces, EDS spectroscopy for the chemical composition, UV-Visible-Nir spectroscopy for determination the optical proprieties of thin films.The experimental results show that: the films have hexagonal structure at the type (wurtzite), the average size of grains varies from 20.11 to 32.45 nm, the transmittance of the films equals 80% in visible rang and the band gap is varied between 3.274 and 3.282 eV, when the solution flow rate increases from 50 to 150 ml/h.

Visible electroluminescence from a ZnO nanowires/p-GaN heterojunction light emitting diode.

PubMed

Baratto, C; Kumar, R; Comini, E; Faglia, G; Sberveglieri, G

2015-07-27

In the current paper we apply catalyst assisted vapour phase growth technique to grow ZnO nanowires (ZnO nws) on p-GaN thin film obtaining EL emission in reverse bias regime. ZnO based LED represents a promising alternative to III-nitride LEDs, as in free devices: the potential is in near-UV emission and visible emission. For ZnO, the use of nanowires ensures good crystallinity of the ZnO, and improved light extraction from the interface when the nanowires are vertically aligned. We prepared ZnO nanowires in a tubular furnace on GaN templates and characterized the p-n ZnO nws/GaN heterojunction for LED applications. SEM microscopy was used to study the growth of nanowires and device preparation. Photoluminescence (PL) and Electroluminescence (EL) spectroscopies were used to characterize the heterojunction, showing that good quality of PL emission is observed from nanowires and visible emission from the junction can be obtained from the region near ZnO contact, starting from onset bias of 6V.

Nanocrystalline TiO₂ Composite Films for the Photodegradation of Formaldehyde and Oxytetracycline under Visible Light Irradiation.

PubMed

Wei, Min; Peng, Xue-Lei; Liu, Qi-Sheng; Li, Fang; Yao, Ming-Ming

2017-06-14

In order to effectively photodegradate organic pollutants, ZnO composite and Co-B codoped TiO₂ films were successfully deposited on glass substrates via a modified sol-gel method and a controllable dip-coating technique. Combining with UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL) analyses, the multi-modification could not only extend the optical response of TiO₂ to visible light region but also decrease the recombination rate of electron-hole pairs. XRD results revealed that the multi-modified TiO₂ film had an anatase-brookite biphase heterostructure. FE-SEM results indicated that the multi-modified TiO₂ film without cracks was composed of smaller round-like nanoparticles compared to pure TiO₂. BET surface area results showed that the specific surface area of pure TiO₂ and the multi-modified TiO₂ sample was 47.8 and 115.8 m²/g, respectively. By degradation of formaldehyde and oxytetracycline, experimental results showed that the multi-modified TiO₂ film had excellent photodegradation performance under visible light irradiation.

Facile sonochemical synthesis of Ag modified Bi{sub 4}Ti{sub 3}O{sub 12} nanoparticles with enhanced photocatalytic activity under visible light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dutta, Dimple P., E-mail: dimpled@barc.gov.in; Tyagi, A.K.

2016-02-15

Highlights: • Ag doped/dispersed Bi{sub 4}Ti{sub 3}O{sub 12} nanoparticles synthesized sonochemically. • Undoped Bi{sub 4}Ti{sub 3}O{sub 12} exhibited 100% RhB degradation in 45 min under UV light. • Under visible light 100% RhB degradation occured with Bi{sub 4}Ti{sub 3}O{sub 12} in 150 min. • Improved photodegradation of RhB by Ag doped Bi{sub 4}Ti{sub 3}O{sub 12} in visible light. • The Bi{sub 4}Ti{sub 3}O{sub 12}:Ag(5%) sample photodegrades RhB from wastewater under sunlight. - Abstract: Unmodified and Ag modified Bi{sub 4}Ti{sub 3}O{sub 12}:Ag(x%) (x = 2 and 5) nanoparticles have been synthesized sonochemically and characterized using X-ray diffraction, X-ray photoelectron spectroscopy (XPS),more » Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy (SEM), energy dispersion X-ray spectrum (EDS) analysis, transmission electron microscopy (TEM) and UV–vis diffuse reflectance spectroscopy. In the presence of unmodified Bi{sub 4}Ti{sub 3}O{sub 12} nanoparticles, complete photocatalytic degradation of Rhodamine B (RhB) was observed under UV light within 45 min. However, the response of this material for photodegradation of RhB under visible light was poor and could be greatly enhanced with Ag modification. A possible mechanism for this observation has been discussed in detail. The reusability of the material has also been tested and it has been found to have favorable recycling capability. Moreover, the Ag- modified Bi{sub 4}Ti{sub 3}O{sub 12} has been tested for RhB degradation from a wastewater sample under sunlight and promising results have been obtained.« less

A simple preparation method and characterization of B and N co-doped TiO2 nanotube arrays with enhanced photoelectrochemical performance

NASA Astrophysics Data System (ADS)

Georgieva, J.; Valova, E.; Armyanov, S.; Tatchev, D.; Sotiropoulos, S.; Avramova, I.; Dimitrova, N.; Hubin, A.; Steenhaut, O.

2017-08-01

Highly ordered TiO2 nanotube arrays (TNTA) have attracted much attention due to the excellent photocatalytic, optical and electrical properties. However, their absorption range is limited to ultraviolet (UV) spectrum only due to the wide band gap (3.2 eV). One of the strategies to overcome this problem is doping with boron and nitrogen. They are produced via titanium sheet anodization and subsequent electrochemical treatment of titania in an electrolyte containing boric acid. The as-prepared B-TNTA are annealed in N2 atmosphere at 500 °C for 2 h to obtain B,N-TNTA. The samples are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The B,N-TNTA consist of uniform and well aligned nanotubes with an average inner diameter of 80-100 nm and a length not exceeding 1 μm. The photocurrent response measurements of undoped TNTA, N-doped and B,N-co-doped samples are performed under UV and visible light (Vis) illumination and a comparison is made. The obtained results show that the B,N-doping leads to remarkable photocurrent enhancement and better photocatalytic activity for methyl orange (MO) degradation due to the synergistic effects of B,N-co-doping and lower electron-hole recombination rates.

Combined infrared and ultraviolet-visible spectroscopy matrix-isolated carbon vapor

NASA Technical Reports Server (NTRS)

Kurtz, Joe; Huffman, Donald R.

1990-01-01

Infrared and UV-visible absorption spectra have been measured on the same sample of matrix-isolated carbon vapor in order to establish correlations between absorption intensities of vibrational and electronic transitions as a function of sample annealing. A high degree of correlation has been found between the IR feature at 1998/cm recently assigned to C8 and a UV absorption feature at about 3100 A. Thus, for the first time, direct evidence is given for the assignment of one of the unknown UV-visible features of the long-studied matrix-isolated carbon vapor spectrum.

Effect of RE (Nd3+, Sm3+) oxide on structural, optical properties of Na2O-Li2O-ZnO-B2O3 glass system

NASA Astrophysics Data System (ADS)

Hivrekar, Mahesh M.; Bhoyar, D. N.; Mande, V. K.; Dhole, V. V.; Solunke, M. B.; Jadhav, K. M.

2018-05-01

Zinc borate glass activated with rare earth oxide (Nd2O3, Sm2O3) of Na2O-Li2O-ZnO-B2O3 quaternary system has been prepared successfully by melt quenching method. The nucleation and growth of RE oxide were controlled temperature range 950-1000° C and rapid cooling at room temperature. The physical, structural and optical properties were characterized by using X-ray diffraction (XRD), SEM, Ultraviolet-visible spectroscopy (UV-Vis). XRD and SEM studies confirmed the amorphous nature, surface morphology of prepared zinc borate glass. The physical parameters like density, molar volume, molar mass of Nd3+, Sm3+ doped borate glass are summarized in the present article. The optical absorption spectra along with tauc's plot are presented. The optical energy band gap increases due to the addition of rare earth oxide confirming the role of network modifier.

Spectroscopy: An Introduction for Talented High School Students.

ERIC Educational Resources Information Center

Magyar, Elaine; Magyar, James G.

1989-01-01

Investigates the four week chemistry program in a summer program in science and mathematics. Identifies weekly topics for the program: (1) color and visible spectroscopy; (2) UV spectroscopy, fluorescence, and chemiluminescence; (3) IR and NMR spectroscopy; and (4) lists 12 individual projects. (MVL)

Effect of Zn doping on structural, optical and thermal properties of CeO2 nanoparticles

NASA Astrophysics Data System (ADS)

Ramasamy, V.; Vijayalakshmi, G.

2015-09-01

The undoped and Zn doped CeO2 nanoparticles were synthesized by chemical precipitation method at room temperature. The undoped and Zn doped CeO2 nanoparticles have been characterized by X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), ultraviolet visible and photoluminescence (PL) spectroscopy, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry and differential thermal analysis (TG-DTA). The cubic fluorite structures of the CeO2 nanoparticles were determined by XRD. The influence of particle size on structural parameters such as lattice parameter (a), inter planar distance (d), dislocation density (δ), microstrain (ε), lattice strain (η) and texture co-efficient (TC) were also determined. The lattice strains were determined by Williamson-Hall plot method. The effect of Zn doping with shifting of the bands were observed by UV-Vis spectroscopy and also their optical band gap were determined. The emission spectra and energy band diagram of the undoped and Zn doped samples were derived from PL spectroscopy. The structural bond vibrations of undoped and Zn doped CeO2 nanoparticles were analyzed by FTIR spectroscopy. The thermal property (weight loss and decomposition) of the sample is observed by TG-DTA curve.

Characterization, antibacterial, and neurotoxic effect of Green synthesized nanosilver using Ziziphus spina Christi aqueous leaf extract collected from Riyadh, Saudi Arabia

NASA Astrophysics Data System (ADS)

El-Ansary, Afaf; Warsy, Arjumand; Daghestani, Maha; Merghani, Nada M.; Al-Dbass, Abeer; Bukhari, Wadha; Al-Ojayan, Badryah; Ibrahim, Eiman M.; Al-Qahtani, Asma M.; Shafi Bhat, Ramesa

2018-02-01

The current study aims to synthesize silver nanoparticles using Ziziphus spina Christi (ZSC) or (Sidr) aqueous leaf extract collected from Riyadh, Saudi Arabia. The green synthesis of silver nanoparticles using sidr leaves extract was successful. Production of silver nanoparticles was confirmed through UV-vis Spectrophotometer, particles size and zeta potential analysis, Infra-red spectroscopy, Scanning, and Transmission Electron Microscope (SEM and TEM). The UV-visible spectra showed that the absorption peak existed at 400 nm. SEM analysis showed that the synthesized AgNPs were spherical but in slightly aggregated form. TEM demonstrated different size range of 4-33 nm with an average size of 13. The element analysis profile showed silver signal together with oxygen, calcium, and potassium peaks which might be related to the plant structure. Biological effects of the synthesized AgNPs exhibit satisfactory inhibitory effect against ten tested microorganisms. It inhibited the growth of 5 gram-positive and five gram-negative bacteria. Moreover, AgNPs demonstrated a synergistic effect on the neurotoxicity induced in rat pups with orally administered methyl mercury (MeHg). The present study showed that AgNPs prepared from ZSC might be a promising antimicrobial agent for successful treatment of bacterial infection in intensive care units (ICU) especially in case of antibiotic resistance.

Antibacterial properties of silver nanoparticles synthesized by marine Ochrobactrum sp.

PubMed

Thomas, Roshmi; Janardhanan, Anju; Varghese, Rintu T; Soniya, E V; Mathew, Jyothis; Radhakrishnan, E K

2014-01-01

Metal nanoparticle synthesis is an interesting area in nanotechnology due to their remarkable optical, magnetic, electrical, catalytic and biomedical properties, but there needs to develop clean, non-toxic and environmental friendly methods for the synthesis and assembly of nanoparticles. Biological agents in the form of microbes have emerged up as efficient candidates for nanoparticle synthesis due to their extreme versatility to synthesize diverse nanoparticles with varying size and shape. In the present study, an eco favorable method for the biosynthesis of silver nanoparticles using marine bacterial isolate has been attempted. Very interestingly, molecular identification proved it as a strain of Ochrobactrum anhtropi. In addition, the isolate was found to have the potential to form silver nanoparticles intracellularly at room temperature within 24 h. The biosynthesized silver nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). The UV-visible spectrum of the aqueous medium containing silver nanoparticles showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. The SEM and TEM micrographs revealed that the synthesized silver nanoparticles were spherical in shape with a size range from 38 nm - 85 nm. The silver nanoparticles synthesized by the isolate were also used to explore its antibacterial potential against pathogens like Salmonella Typhi, Salmonella Paratyphi, Vibrio cholerae and Staphylococcus aureus.

Antibacterial properties of silver nanoparticles synthesized by marine Ochrobactrum sp

PubMed Central

Thomas, Roshmi; Janardhanan, Anju; Varghese, Rintu T.; Soniya, E.V.; Mathew, Jyothis; Radhakrishnan, E.K.

2014-01-01

Metal nanoparticle synthesis is an interesting area in nanotechnology due to their remarkable optical, magnetic, electrical, catalytic and biomedical properties, but there needs to develop clean, non-toxic and environmental friendly methods for the synthesis and assembly of nanoparticles. Biological agents in the form of microbes have emerged up as efficient candidates for nanoparticle synthesis due to their extreme versatility to synthesize diverse nanoparticles with varying size and shape. In the present study, an eco favorable method for the biosynthesis of silver nanoparticles using marine bacterial isolate has been attempted. Very interestingly, molecular identification proved it as a strain of Ochrobactrum anhtropi. In addition, the isolate was found to have the potential to form silver nanoparticles intracellularly at room temperature within 24 h. The biosynthesized silver nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). The UV-visible spectrum of the aqueous medium containing silver nanoparticles showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. The SEM and TEM micrographs revealed that the synthesized silver nanoparticles were spherical in shape with a size range from 38 nm – 85 nm. The silver nanoparticles synthesized by the isolate were also used to explore its antibacterial potential against pathogens like Salmonella Typhi, Salmonella Paratyphi, Vibrio cholerae and Staphylococcus aureus. PMID:25763025

Electromechanical Behavior of Chemically Reduced Graphene Oxide and Multi-walled Carbon Nanotube Hybrid Material

NASA Astrophysics Data System (ADS)

Benchirouf, Abderrahmane; Müller, Christian; Kanoun, Olfa

2016-01-01

In this paper, we propose strain-sensitive thin films based on chemically reduced graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) without adding any further surfactants. In spite of the insulating properties of the thin-film-based GO due to the presence functional groups such as hydroxyl, epoxy, and carbonyl groups in its atomic structure, a significant enhancement of the film conductivity was reached by chemical reduction with hydro-iodic acid. By optimizing the MWCNT content, a significant improvement of electrical and mechanical thin film sensitivity is realized. The optical properties and the morphology of the prepared thin films were studied using ultraviolet-visible spectroscopy (UV-Vis) and scanning electron microscope (SEM). The UV-Vis spectra showed the ability to tune the band gap of the GO by changing the MWCNT content, whereas the SEM indicated that the MWCNTs were well dissolved and coated by the GO. Investigations of the piezoresistive properties of the hybrid nanocomposite material under mechanical load show a linear trend between the electrical resistance and the applied strain. A relatively high gauge factor of 8.5 is reached compared to the commercial metallic strain gauges. The self-assembled hybrid films exhibit outstanding properties in electric conductivity, mechanical strength, and strain sensitivity, which provide a high potential for use in strain-sensing applications.

Electromechanical Behavior of Chemically Reduced Graphene Oxide and Multi-walled Carbon Nanotube Hybrid Material.

PubMed

Benchirouf, Abderrahmane; Müller, Christian; Kanoun, Olfa

2016-12-01

In this paper, we propose strain-sensitive thin films based on chemically reduced graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) without adding any further surfactants. In spite of the insulating properties of the thin-film-based GO due to the presence functional groups such as hydroxyl, epoxy, and carbonyl groups in its atomic structure, a significant enhancement of the film conductivity was reached by chemical reduction with hydro-iodic acid. By optimizing the MWCNT content, a significant improvement of electrical and mechanical thin film sensitivity is realized. The optical properties and the morphology of the prepared thin films were studied using ultraviolet-visible spectroscopy (UV-Vis) and scanning electron microscope (SEM). The UV-Vis spectra showed the ability to tune the band gap of the GO by changing the MWCNT content, whereas the SEM indicated that the MWCNTs were well dissolved and coated by the GO. Investigations of the piezoresistive properties of the hybrid nanocomposite material under mechanical load show a linear trend between the electrical resistance and the applied strain. A relatively high gauge factor of 8.5 is reached compared to the commercial metallic strain gauges. The self-assembled hybrid films exhibit outstanding properties in electric conductivity, mechanical strength, and strain sensitivity, which provide a high potential for use in strain-sensing applications.

Effect of TiO2 calcination temperature on the photocatalytic oxidation of gaseous NH3.

PubMed

Wu, Hongmin; Ma, Jinzhu; Zhang, Changbin; He, Hong

2014-03-01

Carbon-modified titanium dioxide (TiO2) was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation (PCO) of gaseous NH3 under visible and UV light. The test results showed that no samples had visible light activity, while the TiO2 calcined at 400°C had the best UV light activity among the series of catalysts, and was even much better than the commercial catalyst P25. The catalysts were then characterized by X-ray diffractometry, Brunauer-Emmett-Teller adsorption analysis, Raman spectroscopy, thermogravimetry/differential scanning calorimetry coupled with mass spectrometry, ultraviolet-visible diffuse reflectance spectra, photoluminescence spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy. It was shown that the carbon species residuals on the catalyst surfaces induced the visible light adsorption of the samples calcined in the low temperature range (< 300°C). However, the surface acid sites played a determining role in the PCO of NH3 under visible and UV light over the series of catalysts. Although the samples calcined at low temperatures had very high SSA, good crystallinity, strong visible light absorption and also low PL emission intensity, they showed very low PCO activity due to their very low number of acid sites for NH3 adsorption and activation. The TiO2 sample calcined at 400°C contained the highest number of acid sites among the series of catalysts, therefore showing the highest performance for the PCO of NH3 under UV light. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Synthesis of gold nanochains via photoactivation technique and their catalytic applications.

PubMed

Sinha, Arun Kumar; Basu, Mrinmoyee; Sarkar, Sougata; Pradhan, Mukul; Pal, Tarasankar

2013-05-15

The article reports a simple photoactivation technique for the synthesis of chain like assembly of spherical Au nanocrystals using a nontoxic biochemical, β-cyclodextrin under ~365 nm UV-light irradiation. Under UV irradiation, β-cyclodextrin acts as a reducing as well as capping agent and eventually becomes a stabilizing linker for Au nanoparticles. The UV-visible spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), and X-ray photoelectron spectroscopic techniques are employed to systematically characterize the Au nanochains. Additionally, it is shown that the Au nanocrystals act as an effective catalyst for the reduction in nitrobenzene to aniline and methylene blue to leuco methylene blue in presence of suitable reducing agent. The catalytic reduction reactions and kinetic parameters are evaluated from UV-visible spectroscopy. Copyright © 2013 Elsevier Inc. All rights reserved.

Synthesis and characterization of zinc-molybdenum oxide photocatalysts using an electrochemical-thermal process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goveas, J. J., E-mail: jenicegoveas@gmail.com; Gonsalves, R. A.; Rao, P.

2016-05-23

Dyes act as major pollutants in water and can be degraded by photocatalysis. This paper establishes the role of electrochemically generated nanostructures of Zinc-Molybdenum oxides (ZMO) as photocatalysts by degrading EBT (Eriochrome Black- T) taken as a model pollutant under UV light. A facile, rapid and low cost process to synthesize these nanostructures (ZMO) is presented. Various factors that affect the synthesis and photocatalytic activity of these nanostructures are discussed. The role of calcination temperature and pulverization on the photocatalytic action has also been established. Particles have been synthesized in pure form as well as using surfactants such as cetrimidemore » (cetyl trimethyl ammonium bromide), polyethylene glycol (PEG) and SDS (sodium dodecyl sulphate) to enhance their photocatalytic action. This paper also discusses the characterization of these nanoparticles by powder XRD, SEM, FT-IR and UV-Visible spectroscopy. Decolourisation was achieved to completion under optimum experimental conditions at room temperature ascertaining the application of these nanostructures as effective photocatalysts.« less

Green synthesis of colloidal copper oxide nanoparticles using Carica papaya and its application in photocatalytic dye degradation.

PubMed

Sankar, Renu; Manikandan, Perumal; Malarvizhi, Viswanathan; Fathima, Tajudeennasrin; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

2014-01-01

Copper oxide (CuO) nanoparticles were synthesized by treating 5 mM cupric sulphate with Carica papaya leaves extract. The kinetics of the reaction was studied using UV-visible spectrophotometry. An intense surface Plasmon resonance between 250-300 nm in the UV-vis spectrum clearly reveals the formation of copper oxide nanoparticles. The results of scanning electron microscopy (SEM) and dynamic light scattering (DLS) exhibited that the green synthesized copper oxide nanoparticles are rod in shape and having a mean particle size of 140 nm, further negative zeta potential disclose its stability at -28.9 mV. The Fourier-transform infrared (FTIR) spectroscopy results examined the occurrence of bioactive functional groups required for the reduction of copper ions. X-ray diffraction (XRD) spectra confirmed the copper oxide nanoparticles crystalline nature. Furthermore, colloidal copper oxide nanoparticles effectively degrade the Coomassie brilliant blue R-250 dye beneath the sunlight. Copyright © 2013 Elsevier B.V. All rights reserved.

Identification of the silver state in the framework of Ag-containing zeolite by XRD, FTIR, photoluminescence, 109Ag NMR, EPR, DR UV-vis, TEM and XPS investigations.

PubMed

Popovych, Nataliia; Kyriienko, Pavlo; Soloviev, Sergiy; Baran, Rafal; Millot, Yannick; Dzwigaj, Stanislaw

2016-10-26

Silver has been identified in the framework of Ag x SiBEA zeolites (where x = 3-6 Ag wt%) by the combined use of XRD, 109 Ag MAS NMR, FTIR, diffuse reflectance UV-visible, EPR and XPS spectroscopy. The incorporation of Ag ions into the framework of SiBEA zeolite has been evidenced by XRD. The consumption of OH groups as a result of their reaction with the silver precursor has been monitored by FTIR and photoluminescence spectroscopy. The changes in the silver state as a function of Ag content and thermal and hydrogen treatment at 573 K have been identified by 109 Ag MAS NMR, EPR, DR UV-visible, TEM and XPS investigations. The acidity of AgSiBEA has been investigated by FTIR spectroscopy of adsorbed CO and pyridine used as probe molecules.

Band edge movement and structural modifications in transition metal doped TiO2 nanocrystals for the application of DSSC

NASA Astrophysics Data System (ADS)

Patle, L. B.; Huse, V. R.; Chaudhari, A. L.

2017-10-01

Nanocrystalline undoped and transition metal ion doped (TM:Cu2+, Mn2+ and Fe3+) TiO2 nanoparticles, with 1 mol% were synthesized by a simple and cost effective modified co-precipitation method at room temperature and were successfully used as photoanode for dye sensitized solar cell (DSSC). The effect of transition metal ions into TiO2 nano crystalline powder has been systematically investigated using x-ray diffraction (XRD), UV-Vis spectroscope, scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive x-ray spectroscopy (EDX). The results of XRD confirm nanocrystalline anatase tetragonal structure of prepared undoped and TM doped TiO2 semiconductor. The influence of doping on band edge movement has been estimated using UV-visible spectroscopy. The SEM results indicate that microscopic effect of doping on morphology of the TiO2. The peaks of EDX signify incorporation of transition metal cations into TiO2 lattice. The effect of doping on flat band potential was estimated using interpolation on Mott-Schottky plot. The performances of DSSCs of undoped and doped TiO2 photoelectrodes were investigated under light illumination. In comparison with undoped and (Cu2+, Fe3+) doped TiO2 photoanodes we found that incorporation of Mn2+ into TiO2 exhibits improvement in photoconversion efficiency (η). There is increase in photoconversion efficiency of DSSCs with Mn2+ doped TiO2 by 6% as compared to that of undoped TiO2 photoanode.

Synthesis of mesoporous zeolite single crystals with cheap porogens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tao Haixiang; Li Changlin; Ren Jiawen

2011-07-15

Mesoporous zeolite (silicalite-1, ZSM-5, TS-1) single crystals have been successfully synthesized by adding soluble starch or sodium carboxymethyl cellulose (CMC) to a conventional zeolite synthesis system. The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen sorption analysis, {sup 27}Al magic angle spinning nuclear magnetic resonance ({sup 27}Al MAS NMR), temperature-programmed desorption of ammonia (NH{sub 3}-TPD) and ultraviolet-visible spectroscopy (UV-vis). The SEM images clearly show that all zeolite crystals possess the similar morphology with particle size of about 300 nm, the TEM images reveal that irregular intracrystalmore » pores are randomly distributed in the whole crystal. {sup 27}Al MAS NMR spectra indicate that nearly all of the Al atoms are in tetrahedral co-ordination in ZSM-5, UV-vis spectra confirm that nearly all of titanium atoms are incorporated into the framework of TS-1. The catalytic activity of meso-ZSM-5 in acetalization of cyclohexanone and meso-TS-1 in hydroxylation of phenol was also studied. The synthesis method reported in this paper is cost-effective and environmental friendly, can be easily expended to prepare other hierarchical structured zeolites. - Graphical abstract: Mesoporous zeolite single crystals were synthesized by using cheap porogens as template. Highlights: > Mesoporous zeolite (silicalite-1, ZSM-5, TS-1) single crystals were synthesized. > Soluble starch or sodium carboxymethyl cellulose (CMC) was used as porogens. > The mesoporous zeolites had connected mesopores although closed pores existed. > Higher catalytic activities were obtained.« less

Generation of photocurrent by visible-light irradiation of conjugated dawson polyoxophosphovanadotungstate-porphyrin copolymers.

PubMed

Azcarate, Iban; Huo, Zhaohui; Farha, Rana; Goldmann, Michel; Xu, Hualong; Hasenknopf, Bernold; Lacôte, Emmanuel; Ruhlmann, Laurent

2015-05-26

Four hybrid polyoxometalate-porphyrin copolymer films were obtained by the electrooxidation of zinc octaethylporphyrin in the presence of four different Dawson-type polyoxometalates bearing two pyridyl groups (POM(py)2) with various spacers. The POM monomers were designed around 1,3,5-trisubstituted benzene rings. Two of the substituents of the benzene ring are linked to the pyridyl groups, and the third is connected to the POM subunit. The four monomers vary in the relative positions of the nitrogen atoms of the pyridine rings or in the distance from the carbonyl group. The monomers were fully characterized by (1)H, (31)P, and (13)C NMR spectroscopy, electrospray mass spectrometry, IR and UV/Vis spectroscopy, and electrochemistry. The copolymers were characterized by UV/Vis spectroscopy, X-ray photoelectron spectroscopy, electrochemistry, and AFM. Their photovoltaic performance under visible light irradiation was investigated by photocurrent transient measurements under visible illumination. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photoelectrochemical Properties of CuS-GeO2-TiO2 Composite Coating Electrode

PubMed Central

Wen, Xinyu; Zhang, Huawei

2016-01-01

The ITO (indium tin oxide) conductive glass-matrix CuS-GeO2-TiO2 composite coating was generated via EPD (electrophoretic deposition) and followed by a sintering treatment at 450°C for 40 minutes. Characterizations of the CuS-GeO2-TiO2 composite coating were taken by SEM (scanning electron microscope), XRD (X-ray diffraction), EDX (energy dispersive X-ray), UV-Vis DRS (ultraviolet-visible diffuse reflection spectrum), and FT-IR (Fourier transform infrared spectroscopy). Results showed that CuS and GeO2 had dispersed in this CuS-GeO2-TiO2 composite coating (mass percentages for CuS and GeO2 were 1.23% and 2.79%, respectively). The electrochemical studies (cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel polarization) of this CuS-GeO2-TiO2 composite coating electrode were performed in pH = 9.51 Na2CO3-NaHCO3 buffer solution containing 0.50 mol/L CH3OH under the conditions of visible light, ultraviolet light (λ = 365 nm), and dark (without light irradiation as control), respectively. Electrochemical studies indicated that this CuS-GeO2-TiO2 composite coating electrode had better photoelectrocatalytic activity than the pure TiO2 electrode in the electrocatalysis of methanol under visible light. PMID:27055277

Photoelectrochemical Properties of CuS-GeO2-TiO2 Composite Coating Electrode.

PubMed

Wen, Xinyu; Zhang, Huawei

2016-01-01

The ITO (indium tin oxide) conductive glass-matrix CuS-GeO2-TiO2 composite coating was generated via EPD (electrophoretic deposition) and followed by a sintering treatment at 450°C for 40 minutes. Characterizations of the CuS-GeO2-TiO2 composite coating were taken by SEM (scanning electron microscope), XRD (X-ray diffraction), EDX (energy dispersive X-ray), UV-Vis DRS (ultraviolet-visible diffuse reflection spectrum), and FT-IR (Fourier transform infrared spectroscopy). Results showed that CuS and GeO2 had dispersed in this CuS-GeO2-TiO2 composite coating (mass percentages for CuS and GeO2 were 1.23% and 2.79%, respectively). The electrochemical studies (cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel polarization) of this CuS-GeO2-TiO2 composite coating electrode were performed in pH = 9.51 Na2CO3-NaHCO3 buffer solution containing 0.50 mol/L CH3OH under the conditions of visible light, ultraviolet light (λ = 365 nm), and dark (without light irradiation as control), respectively. Electrochemical studies indicated that this CuS-GeO2-TiO2 composite coating electrode had better photoelectrocatalytic activity than the pure TiO2 electrode in the electrocatalysis of methanol under visible light.

Sulphured Polyacrylonitrile Composite Analysed by in operando UV-Visible Spectroscopy and 4-electrode Swagelok Cell.

PubMed

Dominko, Robert; Patel, Manu U M; Bele, Marjan; Pejovnik, Stane

2016-01-01

The electrochemical characteristics of sulfurized polyacrylonitrile composite (PAN/S) cathodes were compared with the commonly used carbon/S-based composite material. The difference in the working mechanism of these composites was examined. Analytical investigations were performed on both kinds of cathode electrode composites by using two reliable analytical techniques, in-situ UV-Visible spectroscopy and a four-electrode Swagelok cell. This study differentiates the working mechanisms of PAN/S composites from conventional elemental sulphur/carbon composite and also sheds light on factors that could be responsible for capacity fading in the case of PAN/S composites.

Synthesis and characterization of the Cu2ZnSnS4 system for photovoltaic applications

NASA Astrophysics Data System (ADS)

Sánchez Pinzón, D. L.; Soracá Perez, G. Y.; Gómez Cuaspud, J. A.; López, E. Vera

2017-01-01

This paper focuses on the synthesis and characterization of a ceramic material based on the Cu2ZnSnS4 system, through the implementation of a hydrothermal route. For this purpose, we started from nitrate dissolutions in a 1.0mol L-1 concentration, which were mixed and treated in a teflon lined vessel steel at 280°C for 48h. The Physicochemical characterization of the solid was evaluated by means of ultraviolet visible spectroscopy (UV-VIS), X-ray diffraction (XRD), Raman spectroscopy, scanning and transmission electron microscopy (SEM-TEM) and solid state impedance spectroscopy (IS). The initial characterization through UV measurements confirms a Band-gap around 1.46eV obtained by the Kubelka-Munk method, which demonstrates the effectiveness of the synthesis method in the obtaining of a semiconductor material. The XRD results confirm the obtaining of a crystalline material of pure phase with tetragonal geometry and I-42m space group. The preferential crystalline orientation was achieved along (2 2 0) facet, with crystallite sizes of nanometric order (6.0nm). The morphological aspects evaluated by means electron microscopy, confirmed the homogeneity of the material, showing specifically a series of textural and surface properties of relevant importance. Finally, the electrical characterizations allow to validate the semiconductor behaviour of CZTS system for development of photovoltaic technologies.

A comparison study of rhodamine B photodegradation over nitrogen-doped lamellar niobic acid and titanic acid under visible-light irradiation.

PubMed

Li, Xiukai; Kikugawa, Naoki; Ye, Jinhua

2009-01-01

A solid-state reaction method with urea as a nitrogen precursor was used to prepare nitrogen-doped lamellar niobic and titanic solid acids (i.e., HNb(3)O(8) and H(2)Ti(4)O(9)) with different acidities for visible-light photocatalysis. The photocatalytic activities of the nitrogen-doped solid acids were evaluated for rhodamine B (RhB) degradation and the results were compared with those obtained over the corresponding nitrogen-doped potassium salts. Techniques such as XRD, BET, SEM, X-ray photoelectron spectroscopy, and UV-visible diffuse reflectance spectroscopy were adopted to explore the nature of the materials as well as the characteristics of the doped nitrogen species. It was found that the intercalation of the urea precursor helped to stabilize the layered structures of both lamellar solid acids and enabled easier nitrogen doping. The effects of urea intercalation were more significant for the more acidic HNb(3)O(8) sample than for the less acidic H(2)Ti(4)O(9). Compared with the nitrogen-doped KNb(3)O(8) and K(2)Ti(4)O(9) samples, the nitrogen-doped HNb(3)O(8) and H(2)Ti(4)O(9) solid acids absorb more visible light and exhibit a superior activity for RhB photodegradation under visible-light irradiation. The nitrogen-doped HNb(3)O(8) sample performed the best among all the samples. The results of the current study suggest that the protonic acidity of the lamellar solid-acid sample is a key factor that influences nitrogen doping and the resultant visible-light photocatalysis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiao, Li-Na; Wang, H.C.; Shen, Y.

Nanostructured lead chalcogenides (PbX, X = Te, Se, S) were prepared via a simple hydrothermal method. The powder samples were characterized by XRD, SEM, SAED and DRS. Phase composition and microstructure analysis indicate that these samples are pure lead chalcogenides phases and have similar morphologies. These lead chalcogenides display efficient absorption in the UV-visible light range. The photocatalytic properties of lead chalcogenides nanoparticles were evaluated by the photodegradation of Congo red under UV-visible light irradiation in air atmosphere. The Congo red solution can be efficiently degraded under visible light in the presence of lead chalcogenides nanoparticles. The photocatalytic activities ofmore » lead chalcogenides generally increase with increasing their band gaps and shows no appreciable loss after repeated cycles. Our results may be useful for developing new photocatalyst systems responsive to visible light among narrow band gap semiconductors.« less

Microwave-assisted synthesis and characterization of nickel ferrite nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carpenter, Gopal; Sen, Ravindra; Gupta, Nitish, E-mail: nitish.nidhi75@gmail.com

2015-08-28

Nickel ferrite nanoparticles (NiFe{sub 2}O{sub 4}) were successfully prepared by microwave-assisted combustion method (MWAC) using citric Electron acid as a chelating agent. NiFe{sub 2}O{sub 4} nanoparticles were characterized by X-ray diffraction (XRD) pattern, Scanning Microscopy (SEM), Fourier transform infrared (FTIR) and UV-Visible techniques. XRD analysis revealed that NiFe{sub 2}O{sub 4} nanoparticles have spinel cubic structure with the average crystalline size of 26.38 nm. SEM analysis revealed random and porous structural morphology of particles and FTIR showed absorption bands related to octahedral and tetrahedral sites, in the range 400–600cm{sup −1} which strongly favor the formation of NiFe{sub 2}O{sub 4} nanoparticles. The opticalmore » band gap is determined by UV Visible method and found to be 5.4 eV.« less

A study of the UV and VUV degradation of FEP

NASA Technical Reports Server (NTRS)

George, Graeme A.; Hill, David J. T.; Odonnell, James H.; Pomery, Peter J.; Rasoul, Firas A.

1993-01-01

UV and VUV degradation of fluorinated ethylene propylene (FEP) copolymer was studied using electron spin resonance (ESR) spectroscopy, x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The ESR study revealed the formation of a terminal polymer radical. The stability of this radical was investigated under different environments. An XPS study of FEP film exposed to VUV and atomic oxygen showed that oxidation takes place on the polymer surface. The study revealed also that the percentage of CF2 in the polymer surface decreased with exposure time and the percentage of CF, CF3, and carbon attached to oxygen increased. SEM micrographs of FEP film exposed to VUV and atomic oxygen identified a rough surface with undulations similar to sand dunes.

Aluminum nitride integrated photonics platform for the ultraviolet to visible spectrum.

PubMed

Lu, Tsung-Ju; Fanto, Michael; Choi, Hyeongrak; Thomas, Paul; Steidle, Jeffrey; Mouradian, Sara; Kong, Wei; Zhu, Di; Moon, Hyowon; Berggren, Karl; Kim, Jeehwan; Soltani, Mohammad; Preble, Stefan; Englund, Dirk

2018-04-30

We demonstrate a wide-bandgap semiconductor photonics platform based on nanocrystalline aluminum nitride (AlN) on sapphire. This photonics platform guides light at low loss from the ultraviolet (UV) to the visible spectrum. We measure ring resonators with intrinsic quality factor (Q) exceeding 170,000 at 638 nm and Q >20,000 down to 369.5 nm, which shows a promising path for low-loss integrated photonics in UV and visible spectrum. This platform opens up new possibilities in integrated quantum optics with trapped ions or atom-like color centers in solids, as well as classical applications including nonlinear optics and on-chip UV-spectroscopy.

One-pot, self-assembled hydrothermal synthesis of 3D flower-like CuS/g-C3N4 composite with enhanced photocatalytic activity under visible-light irradiation

NASA Astrophysics Data System (ADS)

Khan, Azam; Alam, Umair; Raza, Waseem; Bahnemann, D.; Muneer, M.

2018-04-01

Novel visible-light-driven 3D flower-like CuS/g-C3N4 composites have been synthesized by different wt% of CuS using hydrothermal method and characterized by standard analytical techniques such as XRD, FTIR, XPS, BET, UV-Vis DRS spectroscopy, SEM-EDS, and TEM. SEM and TEM analyses showed an intimate interfacial contact between flower-like CuS and g-C3N4 sheet. The synthesized composite materials (CuS/g-C3N4) showed excellent photocatalytic activity for the decolorization of methylene blue (MB) in aqueous suspension under visible-light irradiation, compared with pure CuS and g-C3N4. Among various composites of CuS/g-C3N4, 10 wt% of CuS showed highest photocatalytic activity for the decolorization of dye (MB). This remarkably improved photocatalytic performance of the synthesized materials could be attributed to the synergistic interaction between CuS and g-C3N4, leading to prolonged lifetime of photo-generated e- and h+ pair through the Z-scheme system. A probable Z-scheme mechanism explaining the origin of enhanced performance of the composite material has been proposed. This work not only provides a facile way to synthesize 3D flower-like heterostructure, but also renders rational design for the development of highly efficient Z-scheme photocatalytic systems.

Preparation and characterization of high performance NBR/cobalt (II) chloride coordination composites

NASA Astrophysics Data System (ADS)

Shang, Peng; Shao, Chengli; Li, Qiqing; Wu, Chifei

2018-02-01

Acrylonitrile-butadiene rubber (NBR) composites filled with Cobalt (II) Chloride (CoCl2) particles were prepared by a solvent dispersion method. Acetone was selected as solvent for NBR and CoCl2. To directly enhance the interaction between NBR and CoCl2, a coordination reaction was generated by hot pressing at 200 °C. Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), and x-ray photoelectron spectroscopy (XPS) were employed to investigate the coordination reaction. Results showed that the coordination reaction occurred between the nitrile groups (-CN) of NBR and cobalt ions (Co2+) of CoCl2. Compared with the properties of pure NBR, the tensile strength of NBR/CoCl2 composites filled with 10 parts per hundreds of rubber (phr) CoCl2 increased 2200%. Scanning electron microscopy (SEM) indicated that the CoCl2 particles were dispersed in the NBR matrix homogeneously. The indistinguishable interface between CoCl2 particles and NBR matrix indicated good compatibility. Additionally, thermogravimetric analysis (TGA) showed that coordination reaction improved heat resistance of NBR matrix.

Synthesis, characterization and catalytic activity of nanosized Ni complexed aminoclay

NASA Astrophysics Data System (ADS)

Ranchani, A. Amala Jeya; Parthasarathy, V.; Devi, A. Anitha; Meenarathi, B.; Anbarasan, R.

2017-11-01

A novel Ni complexed aminoclay (AC) catalyst was prepared by complexation method followed by reduction reaction. Various analytical techniques such as FTIR spectroscopy, UV-visible spectroscopy, DSC, TGA, SEM, HRTEM, EDX, XPS and WCA measurement are used to characterize the synthesized material. The AC-Ni catalyst system exhibited improved thermal stability and fiber-like morphology. The XPS results declared the formation of Ni nanoparticles. Thus, synthesized catalyst was tested towards the Schiff base formation reaction between various bio-medical polymers and aniline under air atmosphere at 85 °C for 24 h. The catalytic activity of the catalyst was studied by varying the % weight loading of the AC-Ni system towards the Schiff base formation. The Schiff base formation was quantitatively calculated by the 1H-NMR spectroscopy. While increasing the % weight loading of the AC-Ni catalyst, the % yield of Schiff base was also increased. The k app and Ti values were determined for the reduction of indole and α-terpineol in the presence of AC-Ni catalyst system. The experimental results were compared with the literature report.

Microbial-assisted synthesis and evaluation the cytotoxic effect of tellurium nanorods.

PubMed

Forootanfar, Hamid; Amirpour-Rostami, Sahar; Jafari, Mandana; Forootanfar, Amir; Yousefizadeh, Zahra; Shakibaie, Mojtaba

2015-04-01

The present study was designed to isolate bacterial strain capable of tellurium nanorods' (Te NRs) production followed by purification and evaluation of the cytotoxic effect of Te NRs. Among 25 environmental samples collected for screening of Te NR-producer bacterial strains one bacterial colony (isolated from hot spring and identified as Pseudomonas pseudoalcaligenes strain Te) was selected and applied for biosynthesis of Te NRs. Thereafter, an organic-aqueous partitioning system was applied for the purification of the biogenic Te NRs and the purified Te NRs were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction spectroscopy (XRD), UV-visible spectroscopy, and Fourier transform infrared spectroscopy (FTIR) techniques. The cytotoxic effect of biologically synthesized Te NRs and potassium tellurite on four cell lines of MCF-7, HT1080, HepG2 and A549 was then determined using the MTT assay method. The obtained results revealed lower toxicity for the rod-shaped biogenic tellurium nanostructures (~22nm diameter by 185nm length) compared to K2TeO3. Copyright © 2014. Published by Elsevier B.V.

Hydrogen content estimation of hydrogenated amorphous carbon by visible Raman spectroscopy

NASA Astrophysics Data System (ADS)

Adamopoulos, G.; Robertson, J.; Morrison, N. A.; Godet, C.

2004-12-01

In the present study, we report the hydrogen content estimation of the hydrogenated amorphous carbon (a-C:H) films using visible Raman spectroscopy in a fast and nondestructive way. Hydrogenated diamondlike carbon films were deposited by the plasma enhanced chemical vapor deposition, plasma beam source, and integrated distributed electron cyclotron resonance techniques. Methane and acetylene were used as source gases resulting in different hydrogen content and sp2/sp3 fraction. Ultraviolet-visible (UV-Vis) spectroscopic ellipsometry (1.5-5eV ) as well as UV-Vis spectroscopy were provided with the optical band gap (Tauc gap). The sp2/sp3 fraction and the hydrogen content were independently estimated by electron energy loss spectroscopy and elastic recoil detection analysis-Rutherford back scattering, respectively. The Raman spectra that were acquired in the visible region using the 488nm line shows the superposition of Raman features on a photoluminescence (PL) background. The direct relationship of the sp2 content and the optical band gap has been confirmed. The difference in the PL background for samples of the same optical band gap (sp2 content) and different hydrogen content was demonstrated and an empirical relationship between the visible Raman spectra PL background slope and the corresponding hydrogen content was extracted.

Role of Cu in engineering the optical properties of SnO2 nanostructures: Structural, morphological and spectroscopic studies

NASA Astrophysics Data System (ADS)

Kumar, Virender; Singh, Kulwinder; Jain, Megha; Manju; Kumar, Akshay; Sharma, Jeewan; Vij, Ankush; Thakur, Anup

2018-06-01

We have carried out a systematic study to investigate the effect of Cu doping on the optical properties of SnO2 nanostructures synthesized by chemical route. Synthesized nanostructures were characterized using X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), High resolution transmission electron microscopy (HR-TEM), Energy dispersive X-ray spectroscopy, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, UV-visible and Photoluminescence (PL) spectroscopy. The Rietveld refinement analysis of XRD patterns of Cu-doped SnO2 samples confirmed the formation of single phase tetragonal rutile structure, however some localized distortion was observed for 5 mol% Cu-doped SnO2. Crystallite size was found to decrease with increase in dopant concentration. FE-SEM images indicated change in morphology of samples with doping. HR-TEM images revealed that synthesized nanostructures were nearly spherical and average crystallite size was in the range 12-21 nm. Structural defects, crystallinity and size effects on doping were investigated by Raman spectroscopy and results were complemented by FTIR spectroscopy. Optical band gap of samples was estimated from reflectance spectra. We have shown that band gap of SnO2 can be engineered from 3.62 to 3.82 eV by Cu doping. PL emission intensity increased as the doping concentration increased, which can be attributed to the development of defect states in the forbidden transition region of band gap of SnO2 with doping. We have also proposed a band model owing to defect states in SnO2 to explain the observed PL in Cu doped SnO2 nanostructures.

Enhanced photocatalytic activity for H2 evolution under irradiation of UV-vis light by Au-modified nitrogen-doped TiO2.

PubMed

Zhao, Weirong; Ai, Zhuyu; Dai, Jiusong; Zhang, Meng

2014-01-01

Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV-vis light, respectively. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and photoelectrochemical characterizations. DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV-vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2). This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR) effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of TiO2 and increased the utilization of solar energy, greatly boosting the photocatalytic activity for hydrogen production under UV-vis light.

Synthesis and characterization of germa[n]pericyclynes.

PubMed

Tanimoto, Hiroki; Nagao, Tomohiko; Nishiyama, Yasuhiro; Morimoto, Tsumoru; Iseda, Fumiyasu; Nagato, Yuko; Suzuka, Toshimasa; Tsutsumi, Ken; Kakiuchi, Kiyomi

2014-06-14

The synthesis and characterization of novel pericyclynes comprising germanium atoms and acetylenes, germa[n]pericyclynes, are described. The prepared germa[4]-, [6]-, and [8]pericyclynes were compared by (13)C NMR spectroscopy, X-ray crystallography, cyclic voltammetry, UV-visible spectroscopy, fluorescence emission spectroscopy, Raman spectroscopy, and density functional theory calculation analyses.

UV-visible-DAD and 1H-NMR spectroscopy data fusion for studying the photodegradation process of azo-dyes using MCR-ALS.

PubMed

Fernández, Cristina; Pilar Callao, M; Larrechi, M Soledad

2013-12-15

The photodegradation process of three azo-dyes - Acid Orange 61, Acid Red 97 and Acid Brown 425 - was monitored simultaneously by ultraviolet-visible spectroscopy with diode array detector (UV-vis-DAD) and (1)H-nuclear magnetic resonance ((1)H-NMR). Multivariate curve resolution-alternating least squares (MCR-ALS) was applied to obtain the concentration and spectral profile of the chemical compounds involved in the process. The analysis of the H-NMR data suggests there are more intermediate compounds than those obtained with the UV-vis-DAD data. The fusion of UV-vis-DAD and the (1)H-NMR signal before the multivariate analysis provides better results than when only one of the two detector signals was used. It was concluded that three degradation products were present in the medium when the three azo-dyes had practically degraded. This study is the first application of UV-vis-DAD and (1)H-NMR spectroscopy data fusion in this field and illustrates its potential as a quick method for evaluating the evolution of the azo-dye photodegradation process. © 2013 Elsevier B.V. All rights reserved.

Electrochemical and optical characterization of cobalt, copper and zinc phthalocyanine complexes.

PubMed

Lee, Jaehyun; Kim, Se Hun; Lee, Woosung; Lee, Jiwon; An, Byeong-Kwan; Oh, Se Young; Kim, Jae Pil; Park, Jongwook

2013-06-01

New phthalocyanine (Pc) derivatives that include the alkyl group in ligand were synthesized based on three core metals such as zinc (Zn), copper (Cu), and cobalt (Co). Electrochemical behaviors and optical properties of the new phthalocyanine derivatives with ligand and different core metal were investigated by using cyclic voltammetry, UV-Visible (UV-Vis) spectroscopy and photoluminescence (PL) spectroscopy. In UV-Vis data, maximum values of 2H, Co, Cu, and Zn complexes were 708 nm and 677 nm, 686 nm, 684 nm, respectively.

One dimensional CdS nanowire@TiO2 nanoparticles core-shell as high performance photocatalyst for fast degradation of dye pollutants under visible and sunlight irradiation.

PubMed

Arabzadeh, Abbas; Salimi, Abdollah

2016-10-01

In this study, one-dimensional CdS nanowires@TiO2 nanoparticles core-shell structures (1D CdS NWs@TiO2 NPs) were synthesized by a facile wet chemical-solvothermal method. The different aspects of the properties of CdS NWs@TiO2 NPs were surveyed by using a comprehensive range of characterization techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-vis spectroscopy, scanning electron microscopy (SEM), fluorescence spectroscopy, energy dispersive X-ray spectroscopy (EDX), Cyclic Voltammetry (CV) and amperometry. The as-prepared nanostructure was applied as an effective photocatalyst for degradation of methyl orange (MO), methylene blue (MB) and rhodamine B (Rh B) under visible and sunlight irradiation. The results indicated significantly enhanced photocatalytic activity of CdS NWs@TiO2 NPs for degradation of MO, MB and Rh B compared to CdS NWs. The enhanced photocatalytic activity could be attributed to the enhanced sunlight absorbance and the efficient charge separation of the formed heterostructure between CdS NWs and TiO2. The results showed that MO, Rh B and MB were almost completely degraded after 2, 2 and 3min of exposure to sunlight, respectively; while under visible light irradiation (3W blue LED lamp) the dyes were decomposed with less half degradation rate. The catalytic activity was retained even after three degradation cycles of organic dyes, demonstrating that the proposed nanocomposite can be effectively used as efficient photocatalyst for removal of environmental pollutions caused by organic dyes under sunlight irradiation and it could be an important addition to the field of wastewater treatment. We hope the present study may open a new window of such 1-D semiconductor nanocomposites to be used as visible light photocatalysts in the promising field of organic dyes degradation. Copyright © 2016 Elsevier Inc. All rights reserved.

Biosynthesis and characterization of Acalypha indica mediated copper oxide nanoparticles and evaluation of its antimicrobial and anticancer activity.

PubMed

Sivaraj, Rajeshwari; Rahman, Pattanathu K S M; Rajiv, P; Narendhran, S; Venckatesh, R

2014-08-14

Copper oxide nanoparticles were synthesized by biological method using aqueous extract of Acalypha indica leaf and characterized by UV-visible spectroscopy, XRD, FT-IR, SEM TEM and EDX analysis. The synthesised particles were highly stable, spherical and particle size was in the range of 26-30 nm. The antimicrobial activity of A.indica mediated copper oxide nanoparticles was tested against selected pathogens. Copper oxide nanoparticles showed efficient antibacterial and antifungal effect against Escherichia coli, Pseudomonas fluorescens and Candida albicans. The cytotoxicity activity of A.indica mediated copper nanoparticles was evaluated by MTT assay against MCF-7 breast cancer cell lines and confirmed that copper oxide nanoparticles have cytotoxicity activity. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparative study of Ni and Cu doped ZnO nanoparticles: Structural and optical properties

NASA Astrophysics Data System (ADS)

Thakur, Shaveta; Thakur, Samita; Sharma, Jyoti; Kumar, Sanjay

2018-05-01

Nanoparticles of undoped and doped (0.1 M Ni2+ and Cu2+) ZnO are synthesized using chemical precipitation method. The crystallite size, morphology, chemical bonding and optical properties of as prepared nanoparticles are determined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and UV-visible spectra. XRD analysis shows that the prepared samples are single phase and have hexagonal wurtzite structure. The crystallite size of the doped and undoped nanoparticles is determined using Scherrer method. The crystallite size is found to be increased with concentration of nickel and copper. All stretching and vibrational bands are observed at their specific positions through FTIR. The increase in band gap can be attributed to the different chemical nature of dopant and host cation.

Synthesis of TiO2/functionalized graphene sheets (FGSs) nanocomposites in super critical CO2

NASA Astrophysics Data System (ADS)

Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Chen, Bo; Charpentier, Paul A.

2010-06-01

Highly ordered TiO2 nanowire arrays were prepared on the surface of Functionalized Graphene sheets (FGSs) by solgel method using titanium isopropoxide monomer with acetic acid as the polycondensation agent in the green solvent, supercritical carbon dioxide (sc-CO2). Morphology of synthesized materials was studied by SEM and TEM. Optical properties of the nanocomposites studied by UV spectroscopy which showed high absorption in visible area as well as reduction in their band gap compared to TiO2. By high resolution XPS, chelating bidentate structure of TiO2 with carboxylic group on the surface of graphene sheets can be confirmed. Improvement in the optical properties of the synthesized composites compared to TiO2 alone was confirmed by photocurrent measurements.

A green synthesis method for large area silver thin film containing nanoparticles.

PubMed

Shinde, N M; Lokhande, A C; Lokhande, C D

2014-07-05

The green synthesis method is inexpensive and convenient for large area deposition of thin films. For the first time, a green synthesis method for large area silver thin film containing nanoparticles is reported. Silver nanostructured films are deposited using silver nitrate solution and guava leaves extract. The study confirmed that the reaction time plays a key role in the growth and shape/size control of silver nanoparticles. The properties of silver films are studied using UV-visible spectrophotometer, scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), contact angle, Fourier-transform Raman (FT-Raman) spectroscopy and Photoluminescence (PL) techniques. Finally, as an application, these films are used effectively in antibacterial activity study. Copyright © 2014 Elsevier B.V. All rights reserved.

Progress of reduction of graphene oxide by ascorbic acid

NASA Astrophysics Data System (ADS)

De Silva, K. Kanishka H.; Huang, Hsin-Hui; Yoshimura, Masamichi

2018-07-01

Graphene oxide (GO) and reduced graphene oxide (RGO) are in greater demand in many research fields. As a result, the synthesis of these materials on a large scale in a costeffective manner is more concerned for numerous applications. In the present work, GO was synthesized by oxidizing natural graphite and reduced by ascorbic acid (AA), which is a green reductant. The reduced products obtained at different time periods were in detail characterized by UV-Visible spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopy, Raman spectroscopy, thermogravimetric analysis (TGA), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Results showed that the oxidation of graphite has given highly oxidized GO with a 9.30 Å interlayer space and about 33% of oxygen atomic percentage. Until 50 min of the reduction, both GO and RGO coexist. The reduction rate is fast within the first 30 min. In addition, the suitability of natural graphite over synthetic graphite for the synthesis of GO is shown. The findings of this work pave the way to select GO and RGO for applications of interest in a cheap, green and efficient manner.

Reactive Black 5 dye degradation using filters of smuggled cigarette modified with Fe3.

PubMed

Glugoski, Letícia Polli; de Jesus Cubas, Paloma; Fujiwara, Sérgio Toshio

2017-03-01

This study presents an attempt to solve two serious environmental problems: the generation of toxic effluents and solid waste disposal. The work proposes recycling cigarette filters with the purpose of degrading reactive dyes, which are used in the textile industry. Filters of smuggled cigarettes were recycled through Fe 3+ immobilization on their surface. The material obtained was characterized through Fourier transform infrared spectroscopy (FTIR), atomic absorption spectroscopy (AAS), scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS), and ultraviolet-visible spectroscopy (UV-vis). The factorial design revealed that the most suitable conditions for the degradation of Reactive Black 5 dye were obtained by using 1 g of material at pH 3.0 in a 100 mg L -1 hydrogen peroxide solution. The material showed excellent performance in the Reactive Black 5 dye degradation process; in 60 min, 99.09 % dye was removed. At pH 7.0, the dye degradation was 72.67 %, indicating that the material prepared can be used at pH values greater than 3.0 without the occurrence of hydrated Fe 3+ oxide precipitation. Furthermore, the material showed no loss of catalytic activity after three degradation studies.

Biogenic Silver Nanoparticles by Gelidiella acerosa Extract and their Antifungal Effects

PubMed Central

Vivek, Marimuthu; Kumar, Palanisamy Senthil; Steffi, Sesurajan; Sudha, Sellappa

2011-01-01

The synthesis, characterization and application of biologically synthesized nanomaterials are an important aspect in nanotechnology. The present study deals with the synthesis of silver nanoparticles (Ag-NPs) using the aqueous extract of red seaweed Gelidiella acerosa as the reducing agent to study the antifungal activity. The formation of Ag-NPs was confirmed by UV-Visible Spectroscopy, X-Ray Diffraction (XRD) pattern, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The synthesized Ag-NPs was predominately spherical in shape and polydispersed. Fourier Transform Infra-Red (FT-IR) spectroscopy analysis showed that the synthesized nano-Ag was capped with bimolecular compounds which are responsible for reduction of silver ions. The antifungal effects of these nanoparticles were studied against Humicola insolens (MTCC 4520), Fusarium dimerum (MTCC 6583), Mucor indicus (MTCC 3318) and Trichoderma reesei (MTCC 3929). The present study indicates that Ag-NPs have considerable antifungal activity in comparison with standard antifungal drug, and hence further investigation for clinical applications is necessary. PMID:23408653

Mercury removal in wastewater by iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Vélez, E.; Campillo, G. E.; Morales, G.; Hincapié, C.; Osorio, J.; Arnache, O.; Uribe, J. I.; Jaramillo, F.

2016-02-01

Mercury is one of the persistent pollutants in wastewater; it is becoming a severe environmental and public health problem, this is why nowadays its removal is an obligation. Iron oxide nanoparticles are receiving much attention due to their properties, such as: great biocompatibility, ease of separation, high relation of surface-area to volume, surface modifiability, reusability, excellent magnetic properties and relative low cost. In this experiment, Fe3O4 and γ-Fe2O3 nanoparticles were synthesized using iron salts and NaOH as precipitation agents, and Aloe Vera as stabilizing agent; then these nanoparticles were characterized by three different measurements: first, using a Zetasizer Nano ZS for their size estimation, secondly UV-visible spectroscopy which showed the existence of resonance of plasmon at λmax∼360 nm, and lastly by Scanning Electron Microscopy (SEM) to determine nanoparticles form. The results of this characterization showed that the obtained Iron oxides nanoparticles have a narrow size distribution (∼100nm). Mercury removal of 70% approximately was confirmed by atomic absorption spectroscopy measurements.

Ultraviolet, Visible, and Fluorescence Spectroscopy

NASA Astrophysics Data System (ADS)

Penner, Michael H.

Spectroscopy in the ultraviolet-visible (UV-Vis) range is one of the most commonly encountered laboratory techniques in food analysis. Diverse examples, such as the quantification of macrocomponents (total carbohydrate by the phenol-sulfuric acid method), quantification of microcomponents, (thiamin by the thiochrome fluorometric procedure), estimates of rancidity (lipid oxidation status by the thiobarbituric acid test), and surveillance testing (enzyme-linked immunoassays), are presented in this text. In each of these cases, the analytical signal for which the assay is based is either the emission or absorption of radiation in the UV-Vis range. This signal may be inherent in the analyte, such as the absorbance of radiation in the visible range by pigments, or a result of a chemical reaction involving the analyte, such as the colorimetric copper-based Lowry method for the analysis of soluble protein.

Probing photochromic properties by correlation of UV-visible and infra-red absorption spectroscopy: a case study with cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene.

PubMed

Spangenberg, Arnaud; Piedras Perez, Jose Alejandro; Patra, Abhijit; Piard, Jonathan; Brosseau, Arnaud; Métivier, Rémi; Nakatani, Keitaro

2010-02-01

Quantification of the relative composition of the isomers in a photochromic system at any irradiation time interval is a critical issue in determining absolute quantum yields. For this purpose, we have developed a simple and convenient protocol involving combination of UV-visible and infra-red absorption spectroscopy. Photochromic cyclization reaction of cis-l,2-dicyano-l,2-bis(2,4,5-trimethyl-3-thieny1)ethene (CMTE) is analyzed to demonstrate the efficiency of the proposed methodology. This approach is based on the fact that the two isomers show distinctive infra-red bands. Detailed investigations of the UV-visible and infra-red spectra of the mixture obtained at different irradiation times in CCl(4) supported by quantum chemical computations lead to the unambiguous estimation of molar absorption coefficients of the closed isomer (epsilon(CF) = 4650 L mol(-1) cm(-1) at 512 nm). It facilitates the first determination of absolute quantum yields of this reversible photochromic reaction in CCl(4) by fitting the UV-visible spectral data (Phi(OF-->CF) = 0.41 +/- 0.05 and Phi(CF-->OF) = 0.12 +/- 0.02 at 405 nm and 546 nm, respectively).

Light, Molecules, Action: Using Ultrafast Uv-Visible and X-Ray Spectroscopy to Probe Excited State Dynamics in Photoactive Molecules

NASA Astrophysics Data System (ADS)

Sension, R. J.

2017-06-01

Light provides a versatile energy source capable of precise manipulation of material systems on size scales ranging from molecular to macroscopic. Photochemistry provides the means for transforming light energy from photon to process via movement of charge, a change in shape, a change in size, or the cleavage of a bond. Photochemistry produces action. In the work to be presented here ultrafast UV-Visible pump-probe, and pump-repump-probe methods have been used to probe the excited state dynamics of stilbene-based molecular motors, cyclohexadiene-based switches, and polyene-based photoacids. Both ultrafast UV-Visible and X-ray absorption spectroscopies have been applied to the study of cobalamin (vitamin B_{12}) based compounds. Optical measurements provide precise characterization of spectroscopic signatures of the intermediate species on the S_{1} surface, while time-resolved XANES spectra at the Co K-edge probe the structural changes that accompany these transformations.

Application of Ni-Oxide@TiO₂ Core-Shell Structures to Photocatalytic Mixed Dye Degradation, CO Oxidation, and Supercapacitors.

PubMed

Lee, Seungwon; Lee, Jisuk; Nam, Kyusuk; Shin, Weon Gyu; Sohn, Youngku

2016-12-20

Performing diverse application tests on synthesized metal oxides is critical for identifying suitable application areas based on the material performances. In the present study, Ni-oxide@TiO₂ core-shell materials were synthesized and applied to photocatalytic mixed dye (methyl orange + rhodamine + methylene blue) degradation under ultraviolet (UV) and visible lights, CO oxidation, and supercapacitors. Their physicochemical properties were examined by field-emission scanning electron microscopy, X-ray diffraction analysis, Fourier-transform infrared spectroscopy, and UV-visible absorption spectroscopy. It was shown that their performances were highly dependent on the morphology, thermal treatment procedure, and TiO₂ overlayer coating.

Halide ions complex and deprotonate dipicolinamides and isophthalamides: assessment by mass spectrometry and UV-visible spectroscopy.

PubMed

Carasel, I Alexandru; Yamnitz, Carl R; Winter, Rudolph K; Gokel, George W

2010-12-03

The F(-), Cl(-), and Br(-) binding selectivity of bis(p-nitroanilide)s of dipicolinic and isophthalic acids was studied by using competitive electrospray mass spectrometry and UV-Visible spectroscopy. Both hosts prefer binding Cl(-) over either F(-) or Br(-). Host deprotonation was observed to some extent in all experiments in which the host was exposed to halide ions. When F(-) was present, host deprotonation was often the major process, whereas little deprotonation was observed by Cl(-) or Br(-), which preferred complexation. A solution of either host changed color when mixed with a F(-), H(2)PO(4)(-), di- or triphenylacetate solution.

Quantifying tropical peatland dissolved organic carbon (DOC) using UV-visible spectroscopy.

PubMed

Cook, Sarah; Peacock, Mike; Evans, Chris D; Page, Susan E; Whelan, Mick J; Gauci, Vincent; Kho, Lip Khoon

2017-05-15

UV-visible spectroscopy has been shown to be a useful technique for determining dissolved organic carbon (DOC) concentrations. However, at present we are unaware of any studies in the literature that have investigated the suitability of this approach for tropical DOC water samples from any tropical peatlands, although some work has been performed in other tropical environments. We used water samples from two oil palm estates in Sarawak, Malaysia to: i) investigate the suitability of both single and two-wavelength proxies for tropical DOC determination; ii) develop a calibration dataset and set of parameters to calculate DOC concentrations indirectly; iii) provide tropical researchers with guidance on the best spectrophotometric approaches to use in future analyses of DOC. Both single and two-wavelength model approaches performed well with no one model significantly outperforming the other. The predictive ability of the models suggests that UV-visible spectroscopy is both a viable and low cost method for rapidly analyzing DOC in water samples immediately post-collection, which can be important when working at remote field sites with access to only basic laboratory facilities. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Characterization of dissolved organic matter in Dongjianghu Lake by UV-visible absorption spectroscopy with multivariate analysis.

PubMed

Zhu, Yanzhong; Song, Yonghui; Yu, Huibin; Liu, Ruixia; Liu, Lusan; Lv, Chunjian

2017-08-08

UV-visible absorption spectroscopy coupled with principal component analysis (PCA) and hierarchical cluster analysis (HCA) was applied to characterize spectroscopic components, detect latent factors, and investigate spatial variations of dissolved organic matter (DOM) in a large-scale lake. Twelve surface water samples were collected from Dongjianghu Lake in China. DOM contained lignin and quinine moieties, carboxylic acid, microbial products, and aromatic and alkyl groups, which in the northern part of the lake was largely different from the southern part. Fifteen spectroscopic indices were deduced from the absorption spectra to indicate molecular weight or humification degree of DOM. The northern part of the lake presented the smaller molecular weight or the lower humification degree of DOM than the southern part. E 2/4 , E 3/4 , E 2/3 , and S 2 were latent factors of characterizing the molecular weight of DOM, while E 2/5 , E 3/5 , E 2/6 , E 4/5 , E 3/6 , and A 2/1 were latent factors of evaluating the humification degree of DOM. The UV-visible absorption spectroscopy combined with PCA and HCA may not only characterize DOM fractions of lakes, but may be transferred to other types of waterscape.

CdZnO coated film: A material for photovoltaic applications

NASA Astrophysics Data System (ADS)

Zargar, R. A.; Bhat, M. A.; Reshi, H. A.; Khan, S. D.

2018-06-01

The present study reports structural and optical parameters of wide band gap oxide thick film prepared by screen-printing followed by sintering route. Characterization of the samples was carried out with UV-spectroscopy, XRD, SEM, and Photoluminous study. The XRD and SEM studies reveal that the film deposited is polycrystalline, double phase, and porous with unsymmetrical grain distributions. Optical diffused reflection spectroscopy and Pl measurements give optical band gap of 2.87 eV and near band edge emission at 430 nm.

Removal of Micrometer Size Morphological Defects and Enhancement of Ultraviolet Emission by Thermal Treatment of Ga-Doped ZnO Nanostructures

PubMed Central

Manzoor, Umair; Kim, Do K.; Islam, Mohammad; Bhatti, Arshad S.

2014-01-01

Mixed morphologies of Ga-doped Zinc Oxide (ZnO) nanostructures are synthesized by vapor transport method. Systematic scanning electron microscope (SEM) studies of different morphologies, after periodic heat treatments, gives direct evidence of sublimation. SEM micrographs give direct evidence that morphological defects of nanostructures can be removed by annealing. Ultra Violet (UV) and visible emission depends strongly on the annealing temperatures and luminescent efficiency of UV emission is enhanced significantly with each subsequent heat treatment. X-Ray diffraction (XRD) results suggest that crystal quality improved by annealing and phase separation may occur at high temperatures. PMID:24489725

Removal of micrometer size morphological defects and enhancement of ultraviolet emission by thermal treatment of Ga-doped ZnO nanostructures.

PubMed

Manzoor, Umair; Kim, Do K; Islam, Mohammad; Bhatti, Arshad S

2014-01-01

Mixed morphologies of Ga-doped Zinc Oxide (ZnO) nanostructures are synthesized by vapor transport method. Systematic scanning electron microscope (SEM) studies of different morphologies, after periodic heat treatments, gives direct evidence of sublimation. SEM micrographs give direct evidence that morphological defects of nanostructures can be removed by annealing. Ultra Violet (UV) and visible emission depends strongly on the annealing temperatures and luminescent efficiency of UV emission is enhanced significantly with each subsequent heat treatment. X-Ray diffraction (XRD) results suggest that crystal quality improved by annealing and phase separation may occur at high temperatures.

A novel method for the elaboration of hydroxyapatite with high purity by sol-gel using the albumin and comparison with the classical methods

NASA Astrophysics Data System (ADS)

Mohammed, Eddya; Bouazza, Tbib; Khalil, El-Hami

2018-02-01

In this paper, we report the first synthesis of hydroxyapatite (Hap) by sol-gel using the albumin (egg white) compared with the four classical elaboration methods such as co-precipitation, solid state, and solid-liquid samples of hydroxyapatite. We use a reference sample of hydroxyapatite bought from Fluka Chemika company (Lot and Filling code 385330/1 14599). All samples are characterized by X-ray diffraction (XRD), Uv-visible spectroscopy (Uv-Vis), and Fourier transforms infrared spectroscopy (FT-IR). The XRD study showed the existence of a Hexagonal phase for all our samples prepared in our laboratory and an orthorhombic phase for the Fulka Chemika sample of Hap (Lot and Filling code 385330/1 14599). The study by Uv-visible spectroscopy was performed to determine and compare the optical gap and the disorder of each sample of Hap. The FT-IR spectroscopy demonstrated that all our Hap samples had a similar mode of vibration of the chemical bonds (OH-) and (PO4)3-.

Simple and Precise Quantification of Iron Catalyst Content in Carbon Nanotubes Using UV/Visible Spectroscopy.

PubMed

Agustina, Elsye; Goak, Jeungchoon; Lee, Suntae; Seo, Youngho; Park, Jun-Young; Lee, Naesung

2015-10-01

Iron catalysts have been used widely for the mass production of carbon nanotubes (CNTs) with high yield. In this study, UV/visible spectroscopy was used to determine the Fe catalyst content in CNTs using a colorimetric technique. Fe ions in solution form red-orange complexes with 1,10-phenanthroline, producing an absorption peak at λ=510 nm, the intensity of which is proportional to the solution Fe concentration. A series of standard Fe solutions were formulated to establish the relationship between optical absorbance and Fe concentration. Many Fe catalysts were microscopically observed to be encased by graphitic layers, thus preventing their extraction. Fe catalyst dissolution from CNTs was investigated with various single and mixed acids, and Fe concentration was found to be highest with CNTs being held at reflux in HClO4/HNO3 and H2SO4/HNO3 mixtures. This novel colorimetric method to measure Fe concentrations by UV/Vis spectroscopy was validated by inductively coupled plasma optical emission spectroscopy, indicating its reliability and applicability to asses Fe content in CNTs.

Facile Preparation of Nano-Bi2MoO6/Diatomite Composite for Enhancing Photocatalytic Performance under Visible Light Irradiation

PubMed Central

Gong, Jiuyan; Liu, Jianshe; Song, Wendong; Ji, Lili

2018-01-01

In this work, a new nano-Bi2MoO6/diatomite composite photocatalyst was successfully synthesized by a facile solvothermal method. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV-vis diffuse reflection spectroscopy (DRS) were employed to investigate the morphology, crystal structure, and optical properties. It was shown that nanometer-scaled Bi2MoO6 crystals were well-deposited on the surface of Bi2MoO6/diatomite. The photocatalytic activity of the obtained samples was evaluated by the degradation of rhodamine B (RhB) under the visible light (λ > 420 nm) irradiation. Moreover, trapping experiments were performed to investigate the possible photocatalytic reaction mechanism. The results showed that the nano-Bi2MoO6/diatomite composite with the mass ratio of Bi2MoO6 to diatomaceous earth of 70% exhibited the highest activity, and the RhB degradation efficiency reached 97.6% within 60 min. The main active species were revealed to be h+ and•O2−. As a photocatalytic reactor, its recycling performance showed a good stability and reusability. This new composite photocatalyst material holds great promise in the engineering field for the environmental remediation. PMID:29425138

Spectroscopic and microscopic characterization of silver nanoparticles synthesized using Justicia adhatoda flower

NASA Astrophysics Data System (ADS)

Singh, Tej; Shekhawat, Dharmender Singh; Jyoti, Kumari

2018-05-01

The synthesis of silver nanoparticles (SNPs) by chemical and physical methods produce harmful products which may cause various environmental problems, thus, there is an increasing demand to use ecofriendly methods. Therefore, biosynthesis of SNPs using Justicia adhatoda flower extract is demonstrated in the present study. The biosynthesized SNPs were characterized by UV-visible spectroscopy, Fourier transform-infrared spectroscopy (FTIR), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and atomic force microscopy (AFM) analysis. The result of UV-visible spectroscopy peaked at 417 nm corresponding to the plasmon absorbance of SNPs. The TEM and SAED result reveals the crystalline nature of SNPs. FTIR spectroscopy used to identify the possible biomolecules responsible for the conversion of silver ions to SNPs. The study concluded that Justicia adhatoda flower extract act as an excellent reducing agent and the green synthesized SNPs are safer to the environment.

Hydrogen bonding-assisted interaction between amitriptyline hydrochloride and hemoglobin: spectroscopic and molecular dynamics studies.

PubMed

Maurya, Neha; Maurya, Jitendra Kumar; Kumari, Meena; Khan, Abbul Bashar; Dohare, Ravins; Patel, Rajan

2017-05-01

Herein, we have explored the interaction between amitriptyline hydrochloride (AMT) and hemoglobin (Hb), using steady-state and time-resolved fluorescence spectroscopy, UV-visible spectroscopy, and circular dichroism spectroscopy, in combination with molecular docking and molecular dynamic (MD) simulation methods. The steady-state fluorescence reveals the static quenching mechanism in the interaction system, which was further confirmed by UV-visible and time-resolved fluorescence spectroscopy. The binding constant, number of binding sites, and thermodynamic parameters viz. ΔG, ΔH, ΔS are also considered; result confirms that the binding of the AMT with Hb is a spontaneous process, involving hydrogen bonding and van der Waals interactions with a single binding site, as also confirmed by molecular docking study. Synchronous fluorescence, CD data, and MD simulation results contribute toward understanding the effect of AMT on Hb to interpret the conformational change in Hb upon binding in aqueous solution.

Structural determination of individual chemical species in a mixed system by iterative transformation factor analysis-based X-ray absorption spectroscopy combined with UV-visible absorption and quantum chemical calculation.

PubMed

Ikeda, Atsushi; Hennig, Christoph; Rossberg, André; Tsushima, Satoru; Scheinost, Andreas C; Bernhard, Gert

2008-02-15

A multitechnique approach using extended X-ray absorption fine structure (EXAFS) spectroscopy based on iterative transformation factor analysis (ITFA), UV-visible absorption spectroscopy, and density functional theory (DFT) calculations has been performed in order to investigate the speciation of uranium(VI) nitrate species in acetonitrile and to identify the complex structure of individual species in the system. UV-visible spectral titration suggests that there are four different species in the system, that is, pure solvated species, mono-, di-, and trinitrate species. The pure EXAFS spectra of these individual species are extracted by ITFA from the measured spectral mixtures on the basis of the speciation distribution profile calculated from the UV-visible data. Data analysis of the extracted EXAFS spectra, with the help of DFT calculations, reveals the most probable complex structures of the individual species. The pure solvated species corresponds to a uranyl hydrate complex with an equatorial coordination number (CNeq) of 5, [UO2(H2O)5]2+. Nitrate ions tend to coordinate to the uranyl(VI) ion in a bidentate fashion rather than a unidentate one in acetonitrile for all the nitrate species. The mononitrate species forms the complex of [UO2(H2O)3NO3]+ with a CNeq value of 5, while the di- and trinitrate species have a CNeq value of 6, corresponding to [UO2(H2O)2(NO3)2]0 (D2h) and [UO2(NO3)3]- (D3h), respectively.

Chemical behavior of methylpyranomalvidin-3-O-glucoside in aqueous solution studied by NMR and UV-visible spectroscopy.

PubMed

Oliveira, Joana; Petrov, Vesselin; Parola, A Jorge; Pina, Fernando; Azevedo, Joana; Teixeira, Natércia; Brás, Natércia F; Fernandes, Pedro A; Mateus, Nuno; Ramos, Maria João; de Freitas, Victor

2011-02-17

In the present work, the proton-transfer reactions of the methylpyranomalvidin-3-O-glucoside pigment in water with different pH values was studied by NMR and UV-visible spectroscopies. The results showed four equilibrium forms: the methylpyranomalvidin-3-O-glucoside cation, the neutral quinoidal base, the respective anionic quinoidal base, and a dianionic base unprotonated at the methyl group. According to the NMR data, it seems that for methylpyranomalvidin-3-O-glucoside besides the acid-base equilibrium between the pyranoflavylium cation and the neutral quinoidal base, a new species is formed at pD 4.88-6.10. This is corroborated by the appearance of a new set of signals in the NMR spectrum that may be assigned to the formation of hemiketal/cis-chalcone species to a small extent. The two ionization constants (pK(a1) and pK(a2)) obtained by both methods (NMR and UV-visible) for methylpyranomalvidin-3-O-glucoside are in agreement (pK(a1) = 5.17 ± 0.03; pK(a2) = 8.85 ± 0.08; and pK(a1) = 4.57 ± 0.07; pK(a2) = 8.23 ± 0.04 obtained by NMR and UV-visible spectroscopies, respectively). Moreover, the fully dianionic unprotonated form (at the methyl group) of the methylpyranomalvidin-3-O-glucoside is converted slowly into a new structure that displays a yellow color at basic pH. On the basis of the results obtained through LC-MS and NMR, the proposed structure was found to correspond to the flavonol syringetin-3-glucoside.

Adsorption-photodegradation of humic acid in water by using ZnO coupled TiO2/bamboo charcoal under visible light irradiation.

PubMed

Wang, Xuejiang; Wu, Zhen; Wang, Yin; Wang, Wei; Wang, Xin; Bu, Yunjie; Zhao, Jianfu

2013-11-15

ZnO coupled TiO2/bamboo charcoal (ZnO-TiO2/BC) was prepared using the sol-gel method combined with microwave irradiation. The ZnO-TiO2/BC and TiO2/BC were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N2 adsorption (BET), and UV-vis diffuse reflectance spectroscopy (UV-vis-DRS). The ZnO dopant promoted the transformation of anatase TiO2 to rutile phase, and a significant red shift of absorption edge was brought out due to the interfacial coupling effect between ZnO and TiO2 particles. The BET specific surface area and total pore volume decreased with ZnO doping, indicating that some micropores were blocked. SEM studies indicated that ZnO was almost uniformly deposited on the surface of the ZnO-TiO2/BC. The adsorption and photocatalytic degradation experiments showed that the photo-degrade efficiency for Zno-TiO2/BC was higher than that of TiO2/BC, and for both composites, the removal efficiency of HA increased as pH decreased from 10.0 to 2.0. The degradation of HA by ZnO-TiO2/BC and TiO2/BC fitted well with the Langmuir-Hinshelwood kinetics model, and HA degradation was achieved through a synergistic mechanism of adsorption and photocatalysis. ZnO-TiO2/BC could be used as an effective and alternative photocatalyst for the treatment of water contaminated by organic pollutants. Copyright © 2013 Elsevier B.V. All rights reserved.

Utilization of visible to NIR light energy by Yb+3, Er+3 and Tm+3 doped BiVO4 for the photocatalytic degradation of methylene blue

NASA Astrophysics Data System (ADS)

Regmi, Chhabilal; Kshetri, Yuwaraj K.; Ray, Schindra Kumar; Pandey, Ramesh Prasad; Lee, Soo Wohn

2017-01-01

Lanthanide-doped BiVO4 semiconductors with efficient photocatalytic activities over a broad range of the solar light spectrum have been synthesized by the microwave hydrothermal method using ethylenediaminetetraacetic acid (EDTA). The structural, morphological, and optical properties of the as-synthesized samples were evaluated by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray powder diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, UV-vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The chemical compositions were analyzed by X-ray photoelectron spectroscopy (XPS). The toxicity of the samples was measured using Mus musculus skin melanoma cells (B16-F10 (ATCC® CRL-6475™)) and were found to be nontoxic for human cells. The photocatalytic efficiency of the prepared samples was evaluated by methylene blue (MB) degradation. The best photocatalytic activity was shown by BiVO4 with 6:3:3 mol percentage of Yb+3:Er+3:Tm+3 in all solar light spectrum. The synthesized samples possess low band gap energy and a hollow structure suitable for the better photocatalytic activity. The observed NIR photoactivity supports that the upconversion mechanism is involved in the overall photocatalytic process. Therefore, this approach provides a better alternative upconversion material for integral solar light absorption.

Eco-synthesis of graphene and its use in dihydronicotinamide adenine dinucleotide sensing.

PubMed

Amouzadeh Tabrizi, Mahmoud; Jalilzadeh Azar, Somayeh; Nadali Varkani, Javad

2014-09-01

In this paper, we report a green and eco-friendly approach to synthesize reduced graphene oxide (rGO) via a mild hydrothermal process using malt as a reduced agent. The proposed method is based on the reduction of graphene oxide (GO) in malt solution by making use of the reducing capability of phenolic compounds contained in malt solution. The obtained rGO was characterized by atomic force microscopy (AFM), ultraviolet-visible (UV-vis) absorption spectroscopy, X-ray diffraction spectroscopy (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Electrochemical impedance spectroscopy analysis revealed that the charge transfer resistance of rGO modified glassy carbon (GC) electrode was much lower than that of the GC electrode. The electrochemical behavior of dihydronicotinamide adenine dinucleotide (NADH) on rGO modified GC electrode was investigated by cyclic voltammetry and amperometry. Electrochemical experiments indicated that rGO/GC electrode exhibited excellent electrocatalytic activity toward the NADH, which can be attributed to excellent electrical conductivity and high specific surface area of the rGO composite. The resulting biosensor showed highly sensitive amperometric response to NADH with a low detection limit (0.33μM). Copyright © 2014 Elsevier Inc. All rights reserved.

Preparation of N-doped ZnO-loaded halloysite nanotubes catalysts with high solar-light photocatalytic activity.

PubMed

Cheng, Zhi-Lin; Sun, Wei

2015-01-01

N-doped ZnO nanoparticles were successfully assembled into hollow halloysite nanotubes (HNTs) by using the impregnation method. The catalysts based on N-doped ZnO-loaded HNTs nanocomposites (N-doped ZnO/HNTs) were characterized by X-ray diffraction (XRD), transmission electron microscopy-energy dispersive X-ray (TEM-EDX), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), UV-vis and Fourier transform infrared spectroscopy (FT-IR) techniques. The XRD pattern showed ZnO nanoparticles with hexagonal structure loaded on HNTs. The TEM-EDX analysis indicated ZnO particles with the crystal size of ca.10 nm scattered in hollow structure of HNTs, and furthermore the concentration of N atom in nanocomposites was up to 2.31%. The SEM-EDX verified most of N-ZnO nanoparticles existing in hollow nanotubes of HNTs. Besides containing an obvious ultraviolet absorbance band, the UV-vis spectra of the N-doped ZnO/HNTs catalysts showed an available visible absorbance band by comparing to HNTs and non-doped ZnO/HNTs. The photocatalytic activity of the N-doped ZnO/HNTs catalysts was evaluated by the degradation of methyl orange (MO) solution with the concentration of 20 mg/L under the simulated solar-light irradiation. The result showed that the N-doped ZnO/HNTs catalyst exhibited a desirable solar-light photocatalytic activity.

Synthesis and photocatalytic degradation study of methylene blue dye under visible light irradiation by Fe1-xBixVO4 solid solutions (0 ≤ x ≤ 1.0)

NASA Astrophysics Data System (ADS)

Bera, Ganesh; Reddy, V. R.; Mal, Priyanath; Das, Pradip; Turpu, G. R.

2018-05-01

The novel hetero-structures Fe1-xBixVO4 solid solutions (0 ≤ x ≤ 1.0) with the two dissimilar end member of FeVO4 - BiVO4, were successfully synthesized by the standard solid state reaction method. The structural and chemical properties of as prepared photo-catalyst samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and UV-visible absorption spectroscopy techniques. It is confirmed from the results of XRD, Raman and FT-IR that FeVO4 and BiVO4 are in triclinic (space group P-1 (2)) and monoclinic (space group I2/b (15)) phases respectively. The Bi incorporation into Fe site of FeVO4 emerges as hetero-structures of both the end members of the solid solutions. In addition, the photocatalytic activity in the degradation of methylene blue (MB) dye under visible light irradiation was carried out through UV-visible spectroscopy measurement of photo-catalysts FeVO4, BiVO4 and mixed phases of both photo-catalyst. The results indicate that under visible light irradiation the photocatalytic activity of mixed phases were very effective and higher than the both single phases of the solid solutions. The composition x= 0.25 exhibits an excellent photocatalytic property for the degradation of MB solution under visible light irradiation rather than other.

Teaching UV-Vis Spectroscopy with a 3D-Printable Smartphone Spectrophotometer

ERIC Educational Resources Information Center

Grasse, Elise K.; Torcasio, Morgan H.; Smith, Adam W.

2016-01-01

Visible absorbance spectroscopy is a widely used tool in chemical, biochemical, and medical laboratories. The theory and methods of absorbance spectroscopy are typically introduced in upper division undergraduate chemistry courses, but could be introduced earlier with the right curriculum and instrumentation. A major challenge in teaching…

Visible light photocatalytic activities of template free porous graphitic carbon nitride-BiOBr composite catalysts towards the mineralization of reactive dyes

NASA Astrophysics Data System (ADS)

Kanagaraj, Thamaraiselvi; Thiripuranthagan, Sivakumar; Paskalis, Sahaya Murphin Kumar; Abe, Hideki

2017-12-01

Template free porous g-C3N4 (pGCN) and flower like bismuth oxybromide catalysts were synthesized by poly condensation and precipitation methods respectively. Various weight percentages of porous GCN-BiOBr composite catalysts (x% pGCN-BiOBr where x = 5, 10, 30, 50 & 70 wt% of pGCN) were synthesized by impregnation method. All the synthesized catalysts were characterized by X-Ray diffractometer, Fourier transform infrared spectrophotometer, BET surface area analyzer, UV Visible diffuse reflectance spectrophotometer, X-Ray photoelectron spectrophotometer, SEM with Energy dispersive X-ray analyzer (SEM/EDAX) and elemental mapping, Transmission electron microscope, Photoluminescence spectrophotometer and Electrochemical impedance. Photocatalytic degradation of all the synthesized catalysts were tested towards the harmful reactive dyes such as reactive blue 198 (RB 198), reactive black 5 (RB 5) and reactive yellow 145 (RY 145) in presence of visible irradiation. Among the catalysts 30% pGCN-BiOBr resulted in the highest photocatalytic activity towards the degradation of all the three dyes in presence of UV, visible and solar irradiations. Kinetics studies on the photocatalytic mineralization of dyes indicated that it followed pseudo first order. HPLC, TOC and COD studies confirm that the dyes are mineralized into CO2, water and mineral salts.

Visible light driven photocatalytic degradation of methylene blue using novel camphor sulfonic acid doped polycarbazole/g-C3N4 nanocomposite

NASA Astrophysics Data System (ADS)

Praveena, P.; Dhanavel, S.; Sangamithirai, D.; Narayanan, V.; Stephen, A.

2018-04-01

A novel polycabazole(PCz)/graphitic carbon nitride(g-C3N4) nanocomposite was synthesized via chemical oxidative polymerization method. In the present work, camphor sulfonic acid (CSA) was used as a dopantand ammonium peroxydisulphate (APS) was used as an oxidizing agent. The PCz/g-C3N4 nanocompositewas characterizedusing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and UV-Visible spectroscopy (UV-Vis). The obtained results confirm the successful formation of PCz/g-C3N4 nanocomposite. Visible light induced photocatalytic activity of the novel catalyst was demonstrated using methylene blue as a target pollutant. The results suggestthat PCz/g-C3N4 nanocomposite can be used as an effective catalyst for the degradation of organic pollutants from waste water.

Three-Dimensional BiOI/BiOX (X = Cl or Br) Nanohybrids for Enhanced Visible-Light Photocatalytic Activity

PubMed Central

Liu, Yazi; Xu, Jian; Wang, Liqiong; Zhang, Huayang; Xu, Ping; Duan, Xiaoguang; Sun, Hongqi; Wang, Shaobin

2017-01-01

Three-dimensional flower-like BiOI/BiOX (X = Br or Cl) hybrids were synthesized via a facile one-pot solvothermal approach. With systematic characterizations by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), the Brunauer-Emmett-Teller (BET)specific surface area, X-ray photoelectron spectroscopy (XPS), and the UV-Vis diffuse reflectance spectra (DRS), the BiOI/BiOCl composites showed a fluffy and porous 3-D architecture with a large specific surface area (SSA) and high capability for light absorption. Among all the BiOX (X = Cl, Br, I) and BiOI/BiOX (X = Cl or Br) composites, BiOI/BiOCl stands out as the most efficient photocatalyst under both visible and UV light irradiations for methyl orange (MO) oxidation. The reaction rate of MO degradation on BiOI/BiOCl was 2.1 times higher than that on pure BiOI under visible light. Moreover, BiOI/BiOCl exhibited enhanced water oxidation efficiency for O2 evolution which was 1.5 times higher than BiOI. The enhancement of photocatalytic activity could be attributed to the formation of a heterojunction between BiOI and BiOCl, with a nanoporous structure, a larger SSA, and a stronger light absorbance capacity especially in the visible-light region. The in situ electron paramagnetic resonance (EPR) revealed that BiOI/BiOCl composites could effectively evolve superoxide radicals and hydroxyl radicals for photodegradation, and the superoxide radicals are the dominant reactive species. The superb photocatalytic activity of BiOI/BiOCl could be utilized for the degradation of various industrial dyes under natural sunlight irradiation which is of high significance for the remediation of industrial wastewater in the future. PMID:28336897

Experimental and computational assessment of mycosynthesized CdO nanoparticles towards biomedical applications.

PubMed

S, Gowri; K, Gopinath; A, Arumugam

2018-03-01

The present study reports the biogenic synthesis of Cadmium Oxide Nanoparticles (CdO NPs) using plant pathogenic fungus Nigrospora oryzae culture filtrate. Further, the effect of the NPs on the cancer cell line (HeLa) is explored. The sample was characterized using Thermogravimetric/Differential Thermal (TG/DTA), Powder X-ray Diffraction (XRD), X-ray Photoelectron spectroscopy (XPS), UV-Visible Diffuse Reflectance Spectroscopy (UV-DRS), Field Emission Transmission Electron Microscopy (FE-SEM) with Energy Dispersive X-ray Spectroscopy (EDX), High Resolution Transmission Electron Microscopy (HR-TEM) and Selected Area Electron Diffraction (SAED) analysis. Antibacterial activity was evaluated against both Gram positive and Gram negative bacterial strains and it showed maximum activity against Proteus vulgaris. The larvicidal activity was performed to evaluate the maximum ability of synthesized CdO NPs against Anopheles stephensi. Subsequently, MTT assay also depicted the dose-dependent anticancer activity of CdO NPs against cancer cell line (HeLa). Additionally, the inhibitory effect of CdO NPs was analyzed through extensive docking with cancerous protein agent. Results enlighten that Transketolase protein exhibited high docking score of -4.8 k/mol with H-bond interactions found with Lys75 and Asn185 amino acid residues. DFT study was performed on CdO to understand the charge transfer reaction for the inhibitory mechanism. Convincingly, this study explores the understanding of CdO NPs against HeLa cells. Copyright © 2018. Published by Elsevier B.V.

The critical mission of glycine as a surfactant in the improvement of structural, morphological and optoelectronic features of CdO films

NASA Astrophysics Data System (ADS)

Aydin, Raşit

2018-05-01

The main aim of this study is to examine the effect of glycine as a surfactant agent on the physical properties of CdO films. For this purpose nanostructured CdO films with and without different glycine aggregations (0.5, 1.0 and 2.0 M %) were synthesized on glass bases by SILAR technique. The morphological, structural and optical characteristics of these films have been investigated using MM, SEM, XRD and UV-visible spectroscopy respectively. The MM results showed homogeneous and smooth all films. The SEM graphs showed that by using different glycine concentrations as surfactant, the particle thickness decreased from 366.25 nm to 241.10 nm. XRD results showed that the all CdO films with glycine display a (111) and (200) preferential orientations similar to that of the CdO film without glycine. The direct band gap energy of these films is found to increase from 2.05 to 2.35 eV with increasing the glycine concentration in the bath solution.

Green chemistry approach for the synthesis of biocompatible graphene

PubMed Central

Gurunathan, Sangiliyandi; Han, Jae Woong; Kim, Jin-Hoi

2013-01-01

Background Graphene is a single-atom thick, two-dimensional sheet of hexagonally arranged carbon atoms isolated from its three-dimensional parent material, graphite. One of the most common methods for preparation of graphene is chemical exfoliation of graphite using powerful oxidizing agents. Generally, graphene is synthesized through deoxygenation of graphene oxide (GO) by using hydrazine, which is one of the most widespread and strongest reducing agents. Due to the high toxicity of hydrazine, it is not a promising reducing agent in large-scale production of graphene; therefore, this study focused on a green or sustainable synthesis of graphene and the biocompatibility of graphene in primary mouse embryonic fibroblast cells (PMEFs). Methods Here, we demonstrated a simple, rapid, and green chemistry approach for the synthesis of reduced GO (rGO) from GO using triethylamine (TEA) as a reducing agent and stabilizing agent. The obtained TEA reduced GO (TEA-rGO) was characterized by ultraviolet (UV)–visible absorption spectroscopy, X-ray diffraction (XRD), particle size dynamic light scattering (DLS), scanning electron microscopy (SEM), Raman spectroscopy, and atomic force microscopy (AFM). Results The transition of graphene oxide to graphene was confirmed by UV–visible spectroscopy. XRD and SEM were used to investigate the crystallinity of graphene and the surface morphologies of prepared graphene respectively. The formation of defects further supports the functionalization of graphene as indicated in the Raman spectrum of TEA-rGO. Surface morphology and the thickness of the GO and TEA-rGO were analyzed using AFM. The presented results suggest that TEA-rGO shows significantly more biocompatibility with PMEFs cells than GO. Conclusion This is the first report about using TEA as a reducing as well as a stabilizing agent for the preparation of biocompatible graphene. The proposed safe and green method offers substitute routes for large-scale production of graphene for several biomedical applications. PMID:23940417

Visible light driven photocatalytic degradation of rhodamine B using Mg doped cobalt ferrite spinel nanoparticles synthesized by microwave combustion method

NASA Astrophysics Data System (ADS)

Sundararajan, M.; John Kennedy, L.; Nithya, P.; Judith Vijaya, J.; Bououdina, M.

2017-09-01

Co1-xMgxFe2O4 (0≤x≤0.5) spinel nanoparticles were synthesized by a simple microwave combustion method. The characterization of the samples were performed using X-ray diffraction (XRD) analysis, scanning electron (SEM) microscopy, energy dispersive X-ray (EDX) analysis, UV-visible and diffuse reflectance (DRS) spectroscopy, photoluminescence (PL) spectroscopy, Fourier transformed infrared (FT-IR) spectroscopy and vibrating sample magnetometry (VSM) analysis. The XRD patterns indicate the formation of cubic inverse spinel structure. The calculated average crystallite size using Debye Scherrer's equation is found to be around 46-38 nm. The morphology of spinel nanoparticles was observed from SEM images and the elemental mapping of magnesium doped cobalt ferrite was obtained by using energy dispersive X-ray technique. Optical studies were carried out for the deeper understanding of the conduction band (CB) and valence band (VB) edges of the synthesized nanoparticles. The intrinsic stretching vibrations of Fe3+-O2- in tetrahedral sites leads to the appearance of IR band at around 573 cm-1. The magnetic properties such as remanence magnetization (Mr), coercivity (Hc) and saturation magnetization (Ms) were calculated from the hysteresis curves. The maximum photocatalytic degradation efficiency for Co0.6Mg0.4Fe2O4 is around (99.5%) when compared to that of CoFe2O4 whose efficiency is around (73.0%). The improvement in photocatalytic degradation efficiency is due to the effective separation and prevention of electron-hole pair recombination. The R2 values for the first order rate kinetics are found to be better than R2 values for the second order rate kinetics and this proves that photocatalytic degradation of RhB dye follows first order kinetics. The probable mechanism for the photocatalytic degradation of RhB dye is proposed.

Application of Ni-Oxide@TiO2 Core-Shell Structures to Photocatalytic Mixed Dye Degradation, CO Oxidation, and Supercapacitors

PubMed Central

Lee, Seungwon; Lee, Jisuk; Nam, Kyusuk; Shin, Weon Gyu; Sohn, Youngku

2016-01-01

Performing diverse application tests on synthesized metal oxides is critical for identifying suitable application areas based on the material performances. In the present study, Ni-oxide@TiO2 core-shell materials were synthesized and applied to photocatalytic mixed dye (methyl orange + rhodamine + methylene blue) degradation under ultraviolet (UV) and visible lights, CO oxidation, and supercapacitors. Their physicochemical properties were examined by field-emission scanning electron microscopy, X-ray diffraction analysis, Fourier-transform infrared spectroscopy, and UV-visible absorption spectroscopy. It was shown that their performances were highly dependent on the morphology, thermal treatment procedure, and TiO2 overlayer coating. PMID:28774145

Nanocolloid substrate for surface enhanced Raman scattering sensor for biological applications

USDA-ARS?s Scientific Manuscript database

Biopolymer encapsulated with silver nanoparticle (BeSN) substrate was prepared by chemical reduction method with silver nitrate, trisodium citrate in addition to polyvinyl alcohol. Optical properties of BeSN were analyzed with UV/Vis spectroscopy and hyperspectral microscope imaging. UV/Visible spec...

In-situ fabrication of diketopyrrolopyrrole-carbazole-based conjugated polymer/TiO2 heterojunction for enhanced visible light photocatalysis

NASA Astrophysics Data System (ADS)

Yang, Long; Yu, Yuyan; Zhang, Jianling; Chen, Fu; Meng, Xiao; Qiu, Yong; Dan, Yi; Jiang, Long

2018-03-01

Aiming at developing highly efficient photocatalysts by broadening the light-harvesting region and suppressing photo-generated electron-hole recombination simultaneously, this work reports rational design and fabrication of donor-acceptor (D-A) conjugated polymer/TiO2 heterojunction catalyst with strong interfacial interactions by a facile in-situ thermal treatment. To expand the light-harvesting window, soluable conjugated copolymers with D-A architecture are prepared by Pd-mediated polycondensation of diketopyrrolopyrrole (DPP) and t-butoxycarbonyl (t-Boc) modified carbazole (Car), and used as visible-light-harvesting antenna to couple with TiO2 nanocrystals. The DPP-Car/TiO2 composites show wide range absorption in 300-1000 nm. To improve the interfacial binding at the interface, a facile in-situ thermal treatment is carried out to cleave the pendant t-Boc groups in carbazole units and liberate the polar amino groups (-NH-) which strongly bind to the surface of TiO2 through dipole-dipole interactions, forming a heterojunction interface. This in-situ thermal treatment changes the surface elemental distribution of TiO2, reinforces the interface bonding at the boundary of conjugated polymers/TiO2 and finally improves the photocatalytic efficiency of DPP-Car/TiO2 under visible-light irradiation. The interface changes are characterized and verified through Fourier-transform infrared spectroscopy (FT-IR), photo images, UV/Vis (solution state and powder diffuse reflection spectroscopy), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fluorescence, scanning electron microscopy(SEM) and transmission electron microscopy (TEM) techniques. This study provides a new strategy to avoid the low solubility of D-A conjugated polymers and construct highly-efficient conjugated polymer/TiO2 heterojunction by enforcing the interface contact and facilitating charge or energy transfer for the applications in photocatalysis.

Integrating Elemental Analysis and Chromatography Techniques by Analyzing Metal Oxide and Organic UV Absorbers in Commercial Sunscreens

ERIC Educational Resources Information Center

Quin~ones, Rosalynn; Bayline, Jennifer Logan; Polvani, Deborah A.; Neff, David; Westfall, Tamara D.; Hijazi, Abdullah

2016-01-01

A series of undergraduate laboratory experiments that utilize reversed-phase HPLC separation, inductively coupled plasma spectroscopy (ICP), and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) are described for the analysis of commercial sunscreens. The active ingredients of many sunscreen brands include zinc or titanium…

Formation of hydrogels based on chitosan/alginate for the delivery of lysozyme and their antibacterial activity.

PubMed

Wu, Tiantian; Huang, Jiaqi; Jiang, Yangyang; Hu, Yaqin; Ye, Xingqian; Liu, Donghong; Chen, Jianchu

2018-02-01

Novel hydrogels based on chitosan/sodium alginate (CS-ALG) were prepared to deliver and protect lysozyme while eliminating food-borne microorganisms. These hydrogels were characterized according to the zeta potential, optical microscopy, scanning electron microscopy (SEM), UV-visible spectroscopy (UV-vis), fourier transform infrared (FT-IR), and small-angle X-ray scattering (SAXS). The results demonstrated that the resultant hydrogels were negatively charged and spherical in shape. In addition, the maximum swelling ratio was 45.66±7.62 for CS-ALG hydrogels loaded with lysozyme. The relative activity of the released lysozyme was 87.72±3.96%, indicating that CS-ALG hydrogels are promising matrices for enzyme loading and adsorption. Furthermore, a 100% bacterial clearance rate of CS/ALG loaded with lysozyme was observed to correspond to the superposition effect stimulated by CS and lysozyme, which improved the antibacterial activity against E. coli and S. aureus compared to CS/ALG, suggesting its potential use in the food industry as well as other applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Iron doped SnO2/Co3O4 nanocomposites synthesized by sol-gel and precipitation method for metronidazole antibiotic degradation.

PubMed

Agarwal, Shilpi; Tyagi, Inderjeet; Gupta, Vinod Kumar; Sohrabi, Maryam; Mohammadi, Sanaz; Golikand, Ahmad Nozad; Fakhri, Ali

2017-01-01

Sol-gel and precipitation reaction methods were used to synthesize Un-doped and Fe-doped SnO 2 /Co 3 O 4 nanocomposites under UV light; the synthesized nanocomposites were applied for the photocatalytic degradation of metronidazole antibiotic. The developed photo catalyst was well characterized using energy dispersive X-ray spectrometer (EDX), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FE-SEM), UV-Visible and photoluminescence (PL) spectroscopy. Effective parameters such as pH, photocatalyst dose and contact time was optimized and well investigated. From the obtained facts it is clear that the 98.3% of MTZ was degraded with in 15min, pH6 and 0.1g catalyst when the Fe molar ratio was 1:1 at %. As compared to results obtained from un-doped SnO 2 /Co 3 O 4 nanocomposites Fe doped SnO 2 /Co 3 O 4 nanocomposites possess greater photocatalytic efficiency. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis of carboxylic block copolymers via reversible addition fragmentation transfer polymerization for tooth erosion prevention.

PubMed

Lei, Y; Wang, T; Mitchell, J W; Qiu, J; Kilpatrick-Liverman, L

2014-12-01

Dental professionals are seeing a growing population of patients with visible signs of dental erosion. The approach currently being used to address the problem typically leverages the enamel protection benefits of fluoride. In this report, an alternative new block copolymer with a hydrophilic polyacrylic acid (PAA) block and a hydrophobic poly(methyl methacrylate) (PMMA) block was developed to similarly reduce the mineral loss from enamel under acidic conditions. This series of PMMA-b-PAA block copolymers was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Their structures were characterized by gel permeation chromatography (GPC) and (1)H nuclear magnetic resonance (NMR) spectra. The molar fractions of acrylic acid (AA) in the final block copolymer were finely controlled from 0.25 to 0.94, and the molecular weight (Mn) of PMMA-b-PAA was controlled from 10 kDa to 90 kDa. The binding capability of the block copolymer with hydroxyapatite (HAP) was investigated by ultraviolet-visible spectroscopy (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectra confirmed that the PMMA-b-PAA block copolymer could bind to HAP via bridging bidentate bonds. Both UV-Vis and FTIR spectra additionally indicated that a high polymer concentration and low solution pH favored the polymer binding to HAP. The erosion-preventing efficacy of the PMMA-b-PAA block copolymer in inhibiting HAP mineral loss was quantitatively evaluated by atomic absorption spectroscopy (AAS). Based on the results, polymer treatment reduced the amount of calcium released by 27% to 30% in comparison with the unprotected samples. Scanning electron microscope (SEM) observations indicated that PMMA-b-PAA polymer treatment protected enamel from acid erosion. This new amphiphilic block copolymer has significant potential to be integrated into dentifrices or mouthrinses as an alternative non-fluoride ingredient to reduce tooth erosion. © International & American Associations for Dental Research.

Synthesis of Carboxylic Block Copolymers via Reversible Addition Fragmentation Transfer Polymerization for Tooth Erosion Prevention

PubMed Central

Lei, Y.; Wang, T.; Mitchell, J.W.; Qiu, J.; Kilpatrick-Liverman, L.

2014-01-01

Dental professionals are seeing a growing population of patients with visible signs of dental erosion. The approach currently being used to address the problem typically leverages the enamel protection benefits of fluoride. In this report, an alternative new block copolymer with a hydrophilic polyacrylic acid (PAA) block and a hydrophobic poly(methyl methacrylate) (PMMA) block was developed to similarly reduce the mineral loss from enamel under acidic conditions. This series of PMMA-b-PAA block copolymers was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Their structures were characterized by gel permeation chromatography (GPC) and 1H nuclear magnetic resonance (NMR) spectra. The molar fractions of acrylic acid (AA) in the final block copolymer were finely controlled from 0.25 to 0.94, and the molecular weight (Mn) of PMMA-b-PAA was controlled from 10 kDa to 90 kDa. The binding capability of the block copolymer with hydroxyapatite (HAP) was investigated by ultraviolet–visible spectroscopy (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectra confirmed that the PMMA-b-PAA block copolymer could bind to HAP via bridging bidentate bonds. Both UV-Vis and FTIR spectra additionally indicated that a high polymer concentration and low solution pH favored the polymer binding to HAP. The erosion-preventing efficacy of the PMMA-b-PAA block copolymer in inhibiting HAP mineral loss was quantitatively evaluated by atomic absorption spectroscopy (AAS). Based on the results, polymer treatment reduced the amount of calcium released by 27% to 30% in comparison with the unprotected samples. Scanning electron microscope (SEM) observations indicated that PMMA-b-PAA polymer treatment protected enamel from acid erosion. This new amphiphilic block copolymer has significant potential to be integrated into dentifrices or mouthrinses as an alternative non-fluoride ingredient to reduce tooth erosion. PMID:25248611

Various types of semiconductor photocatalysts modified by CdTe QDs and Pt NPs for toluene photooxidation in the gas phase under visible light

NASA Astrophysics Data System (ADS)

Marchelek, M.; Grabowska, E.; Klimczuk, T.; Lisowski, W.; Zaleska-Medynska, A.

2017-01-01

A novel synthesis process was used to prepare TiO2 microspheres, TiO2 P-25, SrTiO3 and KTaO3 decorated by CdTe QDs and/or Pt NPs. The effect of semiconductor matrix, presence of CdTe QDs and/or Pt NPs on the semiconductor surface as well as deposition technique of Pt NPs (photodeposition or radiolysis) on the photocatalytic activity were investigated. The as-prepared samples were characterized by X-ray powder diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) with energy-dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), photoluminescence spectrometry (PL), Fourier transform infrared (FT-IR) and Raman spectra, diffuse reflectance spectroscopy (DRS) and BET surface area analysis. The photocatalytic decomposition of toluene in gas phase, activated by light-emitting diodes (LEDs), with the CdTe/Pt nanoparticles-modified TiO2 microspheres, P25, SrTiO3 and KTaO3 semiconductors was investigated under UV-vis and visible irradiation.The results showed that the photoactivity depends on semiconductor matrix. The highest photoactivity under Vis light was observed for KTaO3/CdTe-Pt(R) sample (56% of toluene was decompose after 30 min of irradiation). The efficiency of the most active sample was 3 times higher than result for P25 and two times higher than for unmodified KTaO3.

A low volume 3D-printed temperature-controllable cuvette for UV visible spectroscopy.

PubMed

Pisaruka, Jelena; Dymond, Marcus K

2016-10-01

We report the fabrication of a 3D-printed water-heated cuvette that fits into a standard UV visible spectrophotometer. Full 3D-printable designs are provided and 3D-printing conditions have been optimised to provide options to print the cuvette in either acrylonitrile butadiene styrene or polylactic acid polymers, extending the range of solvents that are compatible with the design. We demonstrate the efficacy of the cuvette by determining the critical micelle concentration of sodium dodecyl sulphate at 40 °C, the molar extinction coefficients of cobalt nitrate and dsDNA and by reproducing the thermochromic UV visible spectrum of a mixture of cobalt chloride, water and propan-2-ol. Copyright © 2016 Elsevier Inc. All rights reserved.

Simultaneous infrared and UV-visible absorption spectra of matrix-isolated carbon vapor

NASA Technical Reports Server (NTRS)

Kurtz, Joe; Huffman, Donald R.

1989-01-01

Carbon molecules were suggested as possible carriers of the diffuse interstellar bands. In particular, it was proposed that the 443 nm diffuse interstellar band is due to the same molecule which gives rise to the 447 nm absorption feature in argon matrix-isolated carbon vapor. If so, then an associated C-C stretching mode should be seen in the IR. By doing spectroscopy in both the IR and UV-visible regions on the same sample, the present work provides evidence for correlating UV-visible absorption features with those found in the IR. Early data indicates no correlation between the strongest IR feature (1997/cm) and the 447 nm band. Correlation with weaker IR features is being investigated.

Light-responsive smart surface with controllable wettability and excellent stability.

PubMed

Zhou, Yin-Ning; Li, Jin-Jin; Zhang, Qing; Luo, Zheng-Hong

2014-10-21

Novel fluorinated gradient copolymer was designed for smart surface with light-responsive controllable wettability and excellent stability. The switchable mechanism and physicochemical characteristics of the as-prepared surface decorated by designed polymeric material were investigated by ultraviolet-visible (UV-vis) spectrum, scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS). Thanks to the functional film and surface roughening, etched silicon surface fabricated by copolymer involving spiropyran (Sp) moieties possesses a fairly large variation range of WCA (28.1°) and achieves the transformation between hydrophilicity (95.2° < 109.2°) and hydrophobicity (123.3° > 109.2°) relative to blank sample (109.2°). The synthetic strategy and developed smart surface offer a promising application in coating with controllable wettability, which bridge the gap between chemical structure and material properties.

The adsorption of L-phenylalanine on oxidized single-walled carbon nanotubes.

PubMed

Piao, Lingyu; Liu, Quanrun; Li, Yongdan; Wang, Chen

2009-02-01

A simple and green approach was proceeded to obtain a stable single-walled carbon nanotubes (SWNTs)/L-phenylalanine (Phe) solution. The oxidized SWNTs (OSWNT) were used in this work. The scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HRTEM), Raman spectrometer, Fourier transform-infrared resonance (FT-IR), Ultraviolet-visible (UV-vis) spectroscopy, Thermogravimetric analysis (TGA) and High performance liquid chromatography (HPLC) were joined together to investigate the interaction between OSWNT and Phe. The OSWNT became soluble in the water and formed a stable solution since the Phe was adsorbed. The absorbed amount of Phe on the OSWNT is around 33 wt%. Adsorption of the Phe was mainly carried out on the OSWNT with smaller diameters. The Phe molecules were absorbed on the OSWNT by conjunct interaction of the pi-pi stacking, hydrogen bond and part of covalent bond.

ZnS thin films deposition by thermal evaporation for photovoltaic applications

NASA Astrophysics Data System (ADS)

Benyahia, K.; Benhaya, A.; Aida, M. S.

2015-10-01

ZnS thin films were deposited on glass substrates by thermal evaporation from millimetric crystals of ZnS. The structural, compositional and optical properties of the films are studied by X-ray diffraction, SEM microscopy, and UV-VIS spectroscopy. The obtained results show that the films are pin hole free and have a cubic zinc blend structure with (111) preferential orientation. The estimated optical band gap is 3.5 eV and the refractive index in the visible wavelength ranges from 2.5 to 1.8. The good cubic structure obtained for thin layers enabled us to conclude that the prepared ZnS films may have application as buffer layer in replacement of the harmful CdS in CIGS thin film solar cells or as an antireflection coating in silicon-based solar cells.

Monitoring the growth of polyoxomolybdate nanoparticles in suspension by flow field-flow fractionation.

PubMed

Chen, Bailin; Jiang, Huijian; Zhu, Yan; Cammers, Arthur; Selegue, John P

2005-03-30

We follow the evolution of polyoxomolybdate nanoparticles in suspensions derived from the keplerate (NH4)42[MoVI72MoV60O372(CH3CO2)30(H2O)72].ca..300H2O.ca..10CH3CO2NH4 ({Mo132}) by flow field-flow fractionation (FlFFF) to monitor the particle-size distribution in situ, atomic force and high-resolution transmission electron microscopy (AFM, SEM, and HRTEM) to confirm particle sizes, inductively coupled plasma-optical emission spectrometry (ICP-OES) to determine the Mo content of the FlFFF-separated fractions, and UV/visible spectroscopy to confirm the identity of the species in suspension. We observe the formation of 3-75-nm polyoxomolybdate particles in suspension and the dynamic growth of {Mo132} crystals.

Biosynthesis and characterization of gold nanoparticles using extracts of tamarindus indica L leaves

NASA Astrophysics Data System (ADS)

Correa, S. N.; Naranjo, A. M.; Herrera, A. P.

2016-02-01

This study reports the biosynthesis of gold nanoparticles using an extract of Tamarindus indica L. leaves. Phenols, ketones and carboxyls were present in the leaves of T. indica. These organic compounds that allowed the synthesis of nanoparticles were identified by gas chromatography coupled to mass spectrometry (GC/MS) and High Pressure Liquid Chromatographic (HPLC). Synthesis of gold nanoparticles was performed with the extract of T. indica leaves and an Au+3 aqueous solutions (HAuCl4) at room temperature with one hour of reaction time. Characterization of gold nanoparticles was performed by UV visible spectroscopy, scanning electron microscopy (SEM) and EDX. The results indicated the formation of gold nanoparticles with a wavelength of 576nm and an average size of 52±5nm. The EDX technique confirmed the presence of gold nanoparticles with 12.88% in solution.

Structural and optical properties of WTe2 single crystals synthesized by DVT technique

NASA Astrophysics Data System (ADS)

Dixit, Vijay; Vyas, Chirag; Pathak, V. M.; Soalanki, G. K.; Patel, K. D.

2018-05-01

Layered transition metal di-chalcogenide (LTMDCs) crystals have attracted much attention due to their potential in optoelectronic device applications recently due to realization of their monolayer based structures. In the present investigation we report growth of WTe2 single crystals by direct vapor transport (DVT) technique. These crystals are then characterized by energy dispersive analysis of x-rays (EDAX) to study stoichiometric composition after growth. The structural properties are studied by x-ray diffraction (XRD) and selected area electron diffraction (SAED) is used to confirm orthorhombic structure of grown WTe2 crystal. Surface morphological properties of the crystals are also studied by scanning electron microscope (SEM). The optical properties of the grown crystals are studied by UV-Visible spectroscopy which gives direct band gap of 1.44 eV for grown WTe2 single crystals.

Tailoring surface and photocatalytic properties of ZnO and nitrogen-doped ZnO nanostructures using microwave-assisted facile hydrothermal synthesis

NASA Astrophysics Data System (ADS)

Rangel, R.; Cedeño, V.; Ramos-Corona, A.; Gutiérrez, R.; Alvarado-Gil, J. J.; Ares, O.; Bartolo-Pérez, P.; Quintana, P.

2017-08-01

Microwave hydrothermal synthesis, using an experimental 23 factorial design, was used to produce tunable ZnO nano- and microstructures, and their potential as photocatalysts was explored. Photocatalytic reactions were conducted in a microreactor batch system under UV and visible light irradiation, while monitoring methylene blue degradation, as a model system. The variables considered in the microwave reactor to produce ZnO nano- or microstructures, were time, NaOH concentration and synthesis temperature. It was found that, specific surface area and volume/surface area ratio were affected as a consequence of the synthesis conditions. In the second stage, the samples were plasma treated in a nitrogen atmosphere, with the purpose of introducing nitrogen into the ZnO crystalline structure. The central idea is to induce changes in the material structure as well as in its optical absorption, to make the plasma-treated material useful as photocatalyst in the visible region of the electromagnetic spectrum. Pristine ZnO and nitrogen-doped ZnO compounds were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (BET), XPS, and UV-Vis diffuse reflectance spectroscopy. The results show that the methodology presented in this work is effective in tailoring the specific surface area of the ZnO compounds and incorporation of nitrogen into their structure, factors which in turn, affect its photocatalytic behavior.

Green synthesis of gold nanoparticles using a cheap Sphaeranthus indicus extract: Impact on plant cells and the aquatic crustacean Artemia nauplii.

PubMed

Balalakshmi, Chinnasamy; Gopinath, Kasi; Govindarajan, Marimuthu; Lokesh, Ravi; Arumugam, Ayyakannu; Alharbi, Naiyf S; Kadaikunnan, Shine; Khaled, Jamal M; Benelli, Giovanni

2017-08-01

The impact of green-fabricated gold nanoparticles on plant cells and non-target aquatic species is scarcely studied. In this research, we reported an environment friendly technique for the synthesis of gold nanoparticles (Au NPs) using the Sphaeranthus indicus leaf extract. The formation of the metal NPs was characterized by UV-Visible and FT-IR spectroscopy, XRD, SEM and TEM analyses. The UV-Visible spectra of Au NPs showed a surface plasmon resonance peak at 531nm. FT-IR analysis indicated functional bio-molecules associated with Au NPs formation. The crystalline nature of Au nanoparticles was confirmed by their XRD diffraction pattern. TEM revealed the spherical shape with a mean particle size of 25nm. Au NPs was tested at 0, 1, 3, 5, 7 and 10% doses in mitotic cell division assays, pollen germination experiments, and in vivo toxicity trials against the aquatic crustacean Artemia nauplii. Au NPs did not show any toxic effects on plant cells and aquatic invertebrates. Notably, Au NPs promoted mitotic cell division in Allium cepa root tip cells and germination of Gloriosa superba pollen grains. Au NPs showed no mortality on A. nauplii, all the tested animals showed 100% survivability. Therefore, these Au NPs have potential applications in the development of pollen germination media and plant tissue culture. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation and characterization of zinc and copper co-doped WO3 nanoparticles: Application in photocatalysis and photobiology.

PubMed

Mohammadi, Sanaz; Sohrabi, Maryam; Golikand, Ahmad Nozad; Fakhri, Ali

2016-08-01

In this study, pure, Zn, Cu, Zn,Cu co-doped WO3 nanoparticles samples were prepared by precipitation and co-precipitation methods. These nanoparticles were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDX), Dynamic light scattering (DLS), UV-visible and photoluminescence (PL) spectroscopy. The synthesized pure, Zn, Cu, Zn,Cu co-doped WO3 nanoparticles have smart optical properties and average sizes with 3.2, 3.12, 3.08 and 2.97eV of band-gap, 18.1, 23.2, 25.7 and 30.2nm, respectively. Photocatalytic activity of four nanoparticles was studying towards degradation of gentamicin antibiotic under ultraviolet and visible light irradiation. The result showed that Zn,Cu co-doped WO3 possessed high photocatalytic activity. The photocatalytic activity of WO3 nanoparticles could be remarkably increased by doping the Zn and Cu impurity. This can be attributed to the fact that the red shift of absorption edge and the trapping effect of the mono and co-doped WO3 nanoparticles. The research result presents a general and effective way to prepare different photocatalysts with enhanced visible and UV light-driven photocatalytic performance. Antibacterial activity of four different WO3 nanoparticles against Escherichia coli bacterium has been assessed by the agar disc method under light irradiation and dark medium. It is concluded from the present findings that WO3 nanoparticles can be used as an efficient antibacterial agent. Copyright © 2016 Elsevier B.V. All rights reserved.

Biosynthesis of silver nanoparticles by using Ganoderma-mushroom extract

NASA Astrophysics Data System (ADS)

Ekar, S. U.; Khollam, Y. B.; Koinkar, P. M.; Mirji, S. A.; Mane, R. S.; Naushad, M.; Jadhav, S. S.

2015-03-01

Present study reports the biochemical synthesis of silver nanoparticles (Ag-NPs) from aqueous medium by using the extract of medicinal mushroom Ganoderma, as a reducing and stabilizing agents. The Ag-NPs are prepared at room temperature by the reduction of Ag+ to Ag in aqueous solution of AgNO3. The resultant particles are characterized by using UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) measurement techniques. The formation of Ag-NPs is confirmed by recording the UV-visible absorption spectra for surface plasmon resonance (SPR) where peak around 427 nm. The prominent changes observed in FTIR spectra supported the reduction of Ag+ to Ag. The morphological features of Ag-NPs are evaluated from HRTEM. The spherical Ag-NPs are observed in transmission electron microscopy (TEM) studies. The particle size distribution is found to be nearly uniform with average particle size of 2 nm. The Ag-NPs aged for 15, 30, 60 and 120 days showed no profound effect on the position of SPR peak in UV-visible studies, indicating the protecting/capping ability of medicinal mushroom Ganoderma in the synthesis of Ag-NPs.

Mesoporous CdS via Network of Self-Assembled Nanocrystals: Synthesis, Characterization and Enhanced Photoconducting Property.

PubMed

Patra, Astam K; Banerjee, Biplab; Bhaumik, Asim

2018-01-01

Semiconduction nanoparticles are intensively studied due to their huge potential in optoelctronic applications. Here we report an efficient chemical route for hydrothermal synthesis of aggregated mesoporous cadmium sulfide (CdS) nanoparticles using supramolecular-assembly of ionic and water soluble sodium salicylate as the capping agent. The nanostructure, mesophase, optical property and photoconductivity of these mesoporous CdS materials have been characterized by using small and wide angle powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2-sorption, Raman analysis, Fourier transformed infrared (FT-IR), UV-Visible DSR spectroscopy, and photoconductivity measurement. Wide angle XRD pattern and high resolution TEM image analysis suggested that the particle size of the materials is within 10 nm and the nanoparticles are in well-crystallized cubic phase. Mesoporous CdS nanoparticles showed drastically enhanced photoelectrochemical response under visible light irradiation on entrapping a photosensitizer (dye) molecule in the interparticle spaces. Efficient synthesis strategy and the enhanced photo response in the mesoporous CdS material could facilitate the designing of other porous semiconductor oxide/sulfide and their applications in photon-to-electron conversion processes.

Adsorption and photocatalytic degradation of 2-CP in wastewater onto CS/CoFe₂O ₄ nanocomposite synthesized using gamma radiation.

PubMed

Taleb, Manal F Abou

2014-12-19

Photocatalytic degradation of 2-chlorophenol (2-CP) was studied using the photocatalyst chitosane/CoFe2O4 nanocomposite (CS/CF) under visible light. CS/CF nanocomposites were synthesized via gamma irradiation cross-linking method with the aid of sonication. Physical characteristics of CS/CF were studied using infrared spectrophotometer (IR), scanning electron microscopy (SEM), transmission electron microscope (TEM) and ultraviolet-visible (UV-vis) spectroscopy. Their photocatalytic activity was tested for the degradation of 2-CP in aqueous medium using sunlight. The effect of different parameters such as catalyst concentration, 2-CP concentration and reaction pH on degradation was also examined. It was verified that the 2-CP degradation rate fits a pseudo-first-order kinetics for initial 2-CP concentrations between 25 and 100mg/l, at 30°C. The degradation kinetics fit well Langmuir-Hinshelwood rate law. The degradation of (2-CP) follows pseudo-first-order kinetics. Results showed that after the catalyst had been used 5 times repeatedly, the degradation rate was still above 80%. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synthesis of nanocrystalline NiO/ZnO heterostructured composite powders by sol-gel auto combustion method and their characterizations

NASA Astrophysics Data System (ADS)

Tangcharoen, Thanit; Klysubun, Wantana; Kongmark, Chanapa

2018-03-01

Nanocrystalline NiO/ZnO heterostructured composite powders were prepared by the sol-gel auto combustion method, based on nickel and zinc nitrate precursors and using diethanolamine (DEA) as novel fuel. The composition of different NiO and ZnO ratios, ranging from 100/0, 95/5, 90/10, 80/20, 60/40, 50/50, 40/60, 20/80, 10/90, 5/95 to 0/100, were studied. The structural, chemical bonding, morphological, optical, and fluorescence properties including the local atomic structure of each calcined sample were systematically investigated by means of X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV-visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence (PL) spectroscopy, and synchrotron X-ray absorption spectroscopy (XAS), respectively. For the ZnO concentration below 20%, both XRD and Raman spectroscopy results revealed only the NiO phase. This conformed to the observation of Zn K-edge and Ni K-edge X-ray absorption near edge structure (XANES). The Zn ions found in the samples of low ZnO concentration exhibited six-fold coordination with oxygen atoms rather than the four-fold coordination found in the wurtzite (WZ) structure of ZnO. In contrast, the Ni ions which are found in the samples of low NiO concentration (≤10%) are coordinated both tetrahedrally and octahedrally by four or six oxygen atoms, respectively, rather than the six-fold coordination which is usually observed for Ni ions in the rock salt (RS) form of NiO. All analytical results obtained from experimental XANES spectra were verified by the theoretical calculation of absorption spectra using the FEFF9.7 code. The UV-DRS results showed that there was an increase in the reflectance efficiency for both infrared and visible light conditions as the content of ZnO increases; meanwhile, the values for the energy gap (Eg) of all composite samples were higher than that of pure NiO and ZnO. In addition, the PL spectra revealed major blue emission bands observed at 490 nm when the excitation wavelength was 300 nm. As the ZnO phase developed, a variety of violet emission bands occurred within the range of 400 nm-450 nm, which was obviously related to the change in Eg. The intrinsic defects occurred in the NiO/ZnO composite powders were probably responsible for this phenomenon.

Synthesis and characterization of metal oxide-polyaniline emeraldine salt based nanocomposite

NASA Astrophysics Data System (ADS)

Kumar, K. Siva; Kavitha, B.; Prabakar, K.; Srinivasu, D.; Srinivas, Ch.; Narsimlu, N.

2013-02-01

This paper describes the synthesis of TiO2 (core)/Polyaniline (shell) core-shell structured nanocomposites and characterization of the synthesized material. The morphological characterization is performed with XRD, SEM, DLS and SANS. Spectroscopic characterization is performed with FTIR, UV/Visible and ESR techniques.

Synthesis of a novel glucose capped gold nanoparticle as a better theranostic candidate

PubMed Central

Suvarna, Saritha; Das, Ujjal; KC, Sunil; Mishra, Snehasis; Sudarshan, Mathummal; Saha, Krishna Das; Dey, Sanjit; Chakraborty, Anindita; Narayana, Y.

2017-01-01

Gold nanoparticles are predominantly used in diagnostics, therapeutics and biomedical applications. The present study has been designed to synthesize differently capped gold nanoparticles (AuNps) by a simple, one-step, room temperature procedure and to evaluate the potential of these AuNps for biomedical applications. The AuNps are capped with glucose, 2-deoxy-D-glucose (2DG) and citrate using different reducing agents. This is the first report of synthesis of 2DG-AuNp by the simple room temperature method. The synthesized gold nanoparticles are characterized with UV-Visible Spectroscopy, Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and selected area electron diffraction (SAED), Dynamic light scattering (DLS), and Energy-dispersive X-ray spectroscopy (SEM-EDS). Surface-enhanced Raman scattering (SERS) study of the synthesized AuNps shows increase in Raman signals up to 50 times using 2DG. 3-(4, 5-dimethylthiozol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay has been performed using all the three differently capped AuNps in different cell lines to assess cytotoxcity if any, of the nanoparticles. The study shows that 2DG-AuNps is a better candidate for theranostic application. PMID:28582426

Development of Processing Techniques for Advanced Thermal Protection Materials

NASA Technical Reports Server (NTRS)

Selvaduray, Guna; Cox, Michael; Srinivasan, Vijayakumar

1997-01-01

Thermal Protection Materials Branch (TPMB) has been involved in various research programs to improve the properties and structural integrity of the existing aerospace high temperature materials. Specimens from various research programs were brought into the analytical laboratory for the purpose of obtaining and refining the material characterization. The analytical laboratory in TPMB has many different instruments which were utilized to determine the physical and chemical characteristics of materials. Some of the instruments that were utilized by the SJSU students are: Scanning Electron Microscopy (SEM), Energy Dispersive X-ray analysis (EDX), X-ray Diffraction Spectrometer (XRD), Fourier Transform-Infrared Spectroscopy (FTIR), Ultra Violet Spectroscopy/Visible Spectroscopy (UV/VIS), Particle Size Analyzer (PSA), and Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). The above mentioned analytical instruments were utilized in the material characterization process of the specimens from research programs such as: aerogel ceramics (I) and (II), X-33 Blankets, ARC-Jet specimens, QUICFIX specimens and gas permeability of lightweight ceramic ablators. In addition to analytical instruments in the analytical laboratory at TPMB, there are several on-going experiments. One particular experiment allows the measurement of permeability of ceramic ablators. From these measurements, physical characteristics of the ceramic ablators can be derived.

Biosynthesis of silver nanoparticles using ethanolic petals extract of Rosa indica and characterization of its antibacterial, anticancer and anti-inflammatory activities

NASA Astrophysics Data System (ADS)

Manikandan, Ramar; Manikandan, Beulaja; Raman, Thiagarajan; Arunagirinathan, Koodalingam; Prabhu, Narayanan Marimuthu; Jothi Basu, Muthuramalingam; Perumal, Muthulakshmi; Palanisamy, Subramanian; Munusamy, Arumugam

2015-03-01

The present study was aimed at biosynthesis of silver nanoparticles (AgNPs) using ethanolic extract of rose (Rosa indica) petals and testing their potential antibacterial activity using selective human pathogenic microbes, anticancer activity using human colon adenocarcinoma cancer cell line HCT 15 as well as anti-inflammatory activity using rat peritoneal macrophages in vitro. The biologically synthesized AgNPs were also characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The characterized AgNPs showed an effective antibacterial activity against Gram negative (Escherichia coli, Klebsiella pneumoniae) than Gram positive (Streptococcus mutans, Enterococcus faecalis) bacteria. MTT assay, analysis of nuclear morphology, mRNA expression of Bcl-2, Bax and protein expression of caspase 3 as well as 9, indicated potential anticancer activity. In addition, green synthesized AgNPs also attenuated cytotoxicity, nuclear morphology and free radical generation (O2- and NO) by rat peritoneal macrophages in vitro. The results of our study show the potential green synthesis of silver nanoparticles in mitigating their toxicity while retaining their antibacterial activities.

Modified Fe3O4- hydroxyapatite nanocomposites as heterogeneous catalysts in three UV, Vis and Fenton like degradation systems

NASA Astrophysics Data System (ADS)

Valizadeh, S.; Rasoulifard, M. H.; Dorraji, M. S. Seyed

2014-11-01

The magnetite-hydroxyapatite (M-HAP) nanocomposites were prepared by a chemical co- precipitation procedure and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectra (DRS). The ability of the synthesized catalyst for photocatalytic degradation of Acid Blue 25 (AB25), as an organic dye, under UV irradiation was studied. The catalyst was modified employing transition metals (Mn, Fe, Co, Ni, Cu and Zn) trying to improve the catalytic performance of HAP in absence of UV irradiation and in the presence of hydrogen peroxide i.e. a Fenton like reaction. The best results obtained for Cu and Co modified M-HAPs and the effect of operational parameters such pH, amount of catalyst and hydrogen peroxide concentration was studied. In order to investigate the performance of HAP based photocatalyst in visible light region, M-HAP was modified with silver ions. At the end, Langmuir-Hinshelwood kinetic expression used to evaluate and compare the catalytic systems. The strongest degradation activity was observed for Ag-M-HAP/Vis system because of Ag3PO4 formation. Apparent reaction rate constant (Kapp) by Ag-M-HAP/Vis was 63, 36 and 19 times faster than Cu-M-HAP(II)/H2O2, Co-M-HAP(II)/H2O2 and M-HAP (I)/UV systems, respectively.

Photocatalytic degradation of metronidazole and methylene blue by PVA-assisted Bi2WO6-CdS nanocomposite film under visible light irradiation

NASA Astrophysics Data System (ADS)

Rajendran, Ranjith; Varadharajan, Krishnakumar; Jayaraman, Venkatesan; Singaram, Boobas; Jeyaram, Jayaprakash

2018-02-01

The enhanced photocatalytic performance of nanocomposite is synthesized via the hydrothermal method and characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS) and photoluminescence spectroscopy (PL). Under visible light irradiation, PVA assisted Bi2WO6-CdS nanocomposite film displayed enhanced photocatalytic efficiency and inhibition of photocorrosion as compared with pure CdS, pure Bi2WO6 and Bi2WO6-CdS composite. The PVA assisted Bi2WO6-CdS composite film catalyst showed stable catalytic performance until seven successive runs with 92% of methylene blue(MB) degradation, and easy to recover after degradation of organic pollutant. PVA assisted Bi2WO6-CdS nanocomposite film has optimal band edge position for superior photocatalytic degradation. Furthermore, the trapping experiment was carried out using different scavenger for active species. Among the active species, OH· are the most responsive species which play a vital role in the degradation of metronidazole and MB.

Laser ablation of Au-CuO core-shell nanocomposite in water for optoelectronic devices

NASA Astrophysics Data System (ADS)

Ismail, Raid A.; Abdul-Hamed, Ryam S.

2017-12-01

Core-shell gold-copper oxide Au-CuO nanocomposites were synthesized using laser ablation of CuO target in colloidal solution of Au nanoparticles (NPs). The effect of laser fluence on the structural, morphological, electrical, and optical properties of Au-CuO nanocomposites was investigated using x-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), transmission electron microscope (TEM), photoluminescence (PL), Fourier transformed infrared spectroscopy (FTIR), Hall measurement, and UV-vis spectroscopy. X-ray diffraction results confirm the formation of polycrystalline Au-CuO NPs with monoclinic structure. The optical energy gap for CuO was 4 eV and for the Au-CuO core-shell nanocomposites was found to be in the range of 3.4-3.7 eV. SEM and TEM investigations revealed that the structure and morphology of Au-CuO core-shell nanocomposites were strongly depending on the laser fluence. A formation of Au-CuO nanospheres and platelets structures was observed. The photoluminescence data showed an emission of broad visible peaks between 407 and 420 nm. The effect of laser fluence on the dark and illuminated I-V characteristics of Au-CuO/n-Si heterojunction photodetectors was investigated and analyzed. The experimental data demonstrated that the photodetector prepared at optimum laser fluence exhibited photosensitivity of 0.6 AW-1 at 800 nm.

Fabrication and characterization of high mobility spin-coated zinc oxide thin film transistors

NASA Astrophysics Data System (ADS)

Singh, Shaivalini; Chakrabarti, P.

2012-10-01

A ZnO based thin film transistor (TFT) with bottom-gate configuration and SiO2 as insulating layer has been fabricated and characterized. The ZnO thin film was prepared by spin coating the sol-gel solution on the p-type Si wafers. The optical and structural properties of ZnO films were investigated using UV measurements and scanning electron microscope (SEM). The result of UV-visible study confirms that the films have a good absorbance in UV region and relatively low absorbance in the visible region. The TFT exhibited an off-current of 2.5×10-7 A. The values of field effect channel mobility and on/off current ratio extracted for the device, measured 11 cm2/V.s and ~102 respectively. The value of threshold voltage was found to be 1.3 V.

Fusion of Ultraviolet-Visible and Infrared Transient Absorption Spectroscopy Data to Model Ultrafast Photoisomerization.

PubMed

Debus, Bruno; Orio, Maylis; Rehault, Julien; Burdzinski, Gotard; Ruckebusch, Cyril; Sliwa, Michel

2017-08-03

Ultrafast photoisomerization reactions generally start at a higher excited state with excess of internal vibrational energy and occur via conical intersections. This leads to ultrafast dynamics which are difficult to investigate with a single transient absorption spectroscopy technique, be it in the ultraviolet-visible (UV-vis) or infrared (IR) domain. On one hand, the information available in the UV-vis domain is limited as only slight spectral changes are observed for different isomers. On the other hand, the interpretation of vibrational spectra is strongly hindered by intramolecular relaxation and vibrational cooling. These limitations can be circumvented by fusing UV-vis and IR transient absorption spectroscopy data in a multiset multivariate curve resolution analysis. We apply this approach to describe the spectrodynamics of the ultrafast cis-trans photoisomerization around the C-N double bond observed for aromatic Schiff bases. Twisted intermediate states could be elucidated, and isomerization was shown to occur through a continuous complete rotation. More broadly, data fusion can be used to rationalize a vast range of ultrafast photoisomerization processes of interest in photochemistry.

A facile synthesis of poly(aniline-co-o-bromoaniline) copolymer: Characterization and application as semiconducting material

NASA Astrophysics Data System (ADS)

Mahudeswaran, A.; Vivekanandan, J.; Vijayanand, P. S.; Kojima, T.; Kato, S.

2016-01-01

Poly(aniline-co-o-bromoaniline) (p(an-co-o-BrAn)) copolymer has been synthesized using chemical oxidation method in the hydrochloric acid medium. Copolymerization of aniline with o-bromoaniline of different compositions, such as 1:1, 1:2, 2:1, 1:3 and 3:1 molar ratios were prepared. The synthesized copolymer is soluble in polar solvents like dimethyl sulphoxide (DMSO), dimethyl formamide (DMF), Tetrahydrofuran (THF) and 1-methyl 2-pyrrolidone (NMP). The copolymer is analyzed by various characterization techniques, such as FTIR, UV-Visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), conductivity, Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). FTIR spectrum confirms the characteristic peaks of the copolymer containing benzenoid and quinoid ring stretching. UV spectrum reveals the formation of π-π∗ transition and n-π∗ transition between the energy levels. XRD peaks reveal that the copolymer possesses amorphous nature. Morphological study reveals that the agglomerated particles form globular structure and size of the each particle is about 100 nm. The electrical conductivity of the copolymers is found in the range of 10-5Scm-1. These organic semiconductor materials can be used to fabricate thinner and cheaper environmental friendly optoelectronic devices that will replace the conventional inorganic semiconductors.

Effect of complexing agent on the photoelectrochemical properties of bath deposited CdS thin films

NASA Astrophysics Data System (ADS)

Patil, S. B.; Singh, A. K.

2010-02-01

In the present paper photoelectrochemical (PEC) performance of bath deposited CdS thin films based on complexing agents i.e. ammonia and triethanolamine (TEA) has been discussed. Effect of annealing has also been analyzed. The as-deposited and annealed (at 523 K for 1 h in air) films were characterized by X-ray diffraction (XRD), ultraviolet-visible (UV-vis) absorption spectroscopy, SEM, electrochemical impedance spectroscopy (EIS), and PEC properties. XRD studies revealed that the films were nanocrystalline in nature with mixed hexagonal and cubic phases. TEA complex resulted in better crystallinity. Further improvement in the crystallinity of the films was observed after air annealing. The marigold flower-like structure, in addition to flakes morphology, was observed with TEA complex, whereas for ammonia complex only flakes morphology was observed. The UV-vis absorption studies revealed that the optical absorption edge for the films with ammonia and TEA complex was around 475 nm and 500 nm, respectively. Annealing of the films resulted in red shift in the UV-vis absorption. The PEC cell performance of CdS films was found to be strongly affected by crystallinity and morphology of the films resulted due to complexing agent and annealing. The air annealed film deposited using TEA complex showed maximum short circuit current density ( Jsc) and open circuit voltage ( Voc) i.e. 99 μA/cm 2 and 376 mV respectively, under 10 mW/cm 2 of illumination. The films deposited using TEA complex showed good stability under PEC cell conditions.

Single Step In Situ Synthesis and Optical Properties of Polyaniline/ZnO Nanocomposites

PubMed Central

Kaith, B. S.; Rajput, Jaspreet

2014-01-01

Polyaniline/ZnO nanocomposites were prepared by in situ oxidative polymerization of aniline monomer in the presence of different weight percentages of ZnO nanostructures. The steric stabilizer added to prevent the agglomeration of nanostructures in the polymer matrix was found to affect the final properties of the nanocomposite. ZnO nanostructures of various morphologies and sizes were prepared in the absence and presence of sodium lauryl sulphate (SLS) surfactant under different reaction conditions like in the presence of microwave radiation (microwave oven), under pressure (autoclave), under vacuum (vacuum oven), and at room temperature (ambient condition). The conductivity of these synthesized nanocomposites was evaluated using two-probe method and the effect of concentration of ZnO nanostructures on conductivity was observed. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and UV-visible (UV-VIS) spectroscopy techniques were used to characterize nanocomposites. The optical energy band gap of the nanocomposites was calculated from absorption spectra and ranged between 1.5 and 3.21 eV. The reported values depicted the blue shift in nanocomposites as compared to the band gap energies of synthesized ZnO nanostructures. The present work focuses on the one-step synthesis and potential use of PANI/ZnO nanocomposite in molecular electronics as well as in optical devices. PMID:24523653

Biomimetics of silver nanoparticles by white rot fungus, Phaenerochaete chrysosporium.

PubMed

Vigneshwaran, Nadanathangam; Kathe, Arati A; Varadarajan, P V; Nachane, Rajan P; Balasubramanya, R H

2006-11-01

Extracellular synthesis of silver nanoparticles by a white rot fungus, Phaenerochaete chrysosporium is reported in this paper. Incubation of P. chrysosporium mycelium with silver nitrate solution produced silver nanoparticles in 24h. These silver nanoparticles were characterized by means of UV-vis spectroscopy, X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The synthesized silver nanoparticles absorbed maximum at 470 nm in the visible region. XRD spectrum of the silver nanoparticles confirmed the formation of metallic silver. The SEM characterization of the fungus reacted on the Ag+ indicated that the protein might be responsible for the stabilization of silver nanoparticles. This result was further supported by the TEM examination. Though shape variation was noticed, majority of the nanoparticles were found to be of pyramidal shape as seen under TEM. Photoluminescence spectrum showed a broad emission peak of silver nanoparticles at 423 nm when excited at 350 nm. Apart from eco-friendliness, fungus as bio-manufacturing unit will give us an added advantage in ease of handling when compared to other classes of microorganisms.

Glassy carbon/multi walled carbon nanotube/cadmium sulphide photoanode for light energy storage in vanadium photoelectrochemical cell

NASA Astrophysics Data System (ADS)

Peimanifard, Zahra; Rashid-Nadimi, Sahar

2015-12-01

The aim of this study is utilizing the artificial photosynthesis, which is an attractive and challenging theme in the photoelectrocatalytic water splitting, to charge the vanadium redox flow battery (VRFB). In this work multi walled carbon nanotube/cadmium sulphide hybrid is employed as a photoanode material to oxidize VO2+ toVO2+ for charging the positive vanadium redox flow battery's half-cell. Characterization studies are also described using the scanning electron microscopic-energy-dispersive X-ray spectroscopy (SEM-EDS), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and UV-Visible methods. The phtoelectrochemical performance is characterized by cyclic voltammetry and chronoamperometry. Applied bias photon-to-current efficiency (ABPE) is achieved for both two and three-electrode configurations. The glassy carbon/multi walled carbon nanotube/cadmium sulphide yields high maximum ABPE of 2.6% and 2.12% in three and two-electrode setups, respectively. These results provide a useful guideline in designing photoelectrochemical cells for charging the vanadium redox flow batteries by sunlight as a low cost, free and abundant energy source, which does not rely on an external power input.

Electrical and optical properties of C46H22N8O4KM (M=Co, Fe, Pb) molecular-material thin films prepared by the vacuum thermal evaporation technique.

PubMed

Sánchez-Vergara, M E; Ruiz Farfán, M A; Alvarez, J R; Ponce Pedraza, A; Ortiz, A; Alvarez Toledano, C

2007-03-01

In this work, the synthesis of new materials formed from metallic phthalocyanines (Pcs) and double potassium salt from 1,8-dihydroxianthraquinone is reported. The newly synthesized materials were characterized by scanning electron microscope (SEM), atomic force microscopy (AFM), infrared (IR) and Ultraviolet-visible (UV-vis) spectroscopy. The powder and thin-film samples of the synthesized materials, deposited by vacuum thermal evaporation, show the same intra-molecular bonds as in the IR spectroscopy studies, which suggests that the thermal evaporation process does not alter these bonds. The effect of temperature on conductivity and electrical conduction mechanism was measured in the thin films (approximately 137 nm thickness). They showed a semiconductor-like behaviour with an optical activation energy arising from indirect transitions of 2.15, 2.13 and 3.6eV for the C(46)H(22)N(8)O(4)KFe, C(46)H(22)N(8)O(4)KPb and C(46)H(22)N(8)O(4)KCo thin films.

Electrospun curcumin-loaded cellulose acetate/polyvinylpyrrolidone fibrous materials with complex architecture and antibacterial activity.

PubMed

Tsekova, Petya B; Spasova, Mariya G; Manolova, Nevena E; Markova, Nadya D; Rashkov, Iliya B

2017-04-01

Novel fibrous materials from cellulose acetate (CA) and polyvinylpyrrolidone (PVP) containing curcumin (Curc) with original design were prepared by one-pot electrospinning or dual spinneret electrospinning. The electrospun materials were characterized by scanning electron microscopy (SEM), fluorescence microscopy, Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), differential scanning calorimetry (DSC), water contact angle measurements, and microbiological tests. It was found that the incorporation of Curc into the CA and PVP solutions resulted in an increase of the solution viscosity and obtaining fibers with larger diameters (ca. 1.5μm) compared to the neat CA (ca. 800nm) and PVP fibers (ca. 500nm). The incorporation of PVP resulted in increased hydrophilicity of the fibers and in faster Curc release. Curc was found in the amorphous state in the Curc-containing fibers and these mats exhibited antibacterial activity against Staphylococcus aureus (S. aureus). The results suggest that, due to their complex architecture, the obtained new antibacterial materials are suitable for wound dressing applications, which necessitate diverse release behaviors of the bioactive compound. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation and characterization of host-guest system between inosine and β-cyclodextrin through inclusion mode

NASA Astrophysics Data System (ADS)

Prabu, Samikannu; Sivakumar, Krishnamurty; Swaminathan, Meenakshisundaram; Rajamohan, Rajaram

2015-08-01

Inosine is a nucleoside that is formed when hypoxanthine is attached to a ribose ring (also known as a ribofuranose) via a β-N9-glycosidic bond. Inosine is commonly found in tRNAs. Inosine (INS) has been used widely as an antiviral drug. The inclusion complex of INS with β-CDx in solution phase is studied by ground and excited state with UV-visible and fluorescence spectroscopy, respectively. A binding constant and stoichiometric ratio between INS and β-CDx are calculated by BH equation. The lifetime and relative amplitude of INS is increases with increasing the concentrations of β-CDx, confirms the formation of inclusion complex in liquid state. The solid complexes are prepared by kneading method (KM) and co-precipitation method (CP). The solid complex is characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and differential scanning colorimetry (DSC). CP method gives the solid product with good yield than that of physical mixture and KM method. The structure of complex is proposed based on the study of Patch - Dock server.

Facile method for liquid-exfoliated graphene size prediction by UV-visible spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ismail, Zulhelmi, E-mail: helmie83@hotmail.com; Yusoh, Kamal, E-mail: kamal@ump.edu.my

2016-07-19

In this work, an application of UV spectroscopy for facile prediction of liquid –exfoliated graphene size is discussed. Dynamic light scattering method was used to estimate the graphene flake size ( whilst UV spectroscopy measurement was carried out for extinction coefficient value (ε) determination. It was found that the value of (ε) decreased gradually as the graphene size was further reduced after intense sonication time (7h). This observation showed the influence of sonication time on electronic structure of graphene. A mathematical equation was derived from log-log graph for correlation between () and (ε) value. Both values can be expressed inmore » a single equation as ( = (3.4 × 10{sup −2}) ε{sup 1.2}).« less

Hierarchical nanostructures of copper(II) phthalocyanine on electrospun TiO(2) nanofibers: controllable solvothermal-fabrication and enhanced visible photocatalytic properties.

PubMed

Zhang, Mingyi; Shao, Changlu; Guo, Zengcai; Zhang, Zhenyi; Mu, Jingbo; Cao, Tieping; Liu, Yichun

2011-02-01

In the present work, 2,9,16,23-tetranitrophthalocyanine copper(II) (TNCuPc)/TiO(2) hierarchical nanostructures were successfully fabricated by a simple combination method of electrospinning technique and solvothermal processing. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), UV-vis diffuse reflectance (DR), Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric and differential thermal analysis (TG-DTA) were used to characterize the as-synthesized TNCuPc/TiO(2) hierarchical nanostructures. The results showed that the secondary TNCuPc nanostructures were not only successfully grown on the primary TiO(2) nanofibers substrates but also uniformly distributed without aggregation. By adjusting the solvothermal fabrication parameters, the TNCuPc nanowires or nanoflowers were facilely fabricated, and also the loading amounts of TNCuPc could be controlled on the TNCuPc/TiO(2) hierarchical nanostructural nanofibers. And, there might exist the interaction between TNCuPc and TiO(2). A possible mechanism for the formation of TNCuPc/TiO(2) hierarchical nanostructures was suggested. The photocatalytic studies revealed that the TNCuPc/TiO(2) hierarchical nanostructures exhibited enhanced photocatalytic efficiency of photodegradation of Rhodamine B (RB) compared with the pure TNCuPc or TiO(2) nanofibers under visible-light irradiation.

A plate-on-plate sandwiched Z-scheme heterojunction photocatalyst: BiOBr-Bi2MoO6 with enhanced photocatalytic performance

NASA Astrophysics Data System (ADS)

Wang, Shengyao; Yang, Xianglong; Zhang, Xuehao; Ding, Xing; Yang, Zixin; Dai, Ke; Chen, Hao

2017-01-01

In this study, a direct Z-scheme heterojunction BiOBr-Bi2MoO6 with greatly enhanced visible light photocatalytic performance was fabricated via a two-step coprecipitation method. It was indicated that a plate-on-plate heterojunctions be present between BiOBr and Bi2MoO6 through different characterization techniques including X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS) and photoelectrochemical measurements. The crystal structure and morphology analysis revealed that the heterointerface in BiOBr-Bi2MoO6 occurred mainly on the (001) facets of BiOBr and (001) facets of Bi2MoO6. The photocatalytic activity of the BiOBr-Bi2MoO6 was investigated by degradation of RhB and about 66.7% total organic carbon (TOC) could be removed. Ciprofloxacin (CIP) was employed to rule out the photosensitization. It was implied that the higher activity of BiOBr-Bi2MoO6 could be attribute to the strong redox ability in the Z-scheme system, which was subsequently confirmed by photoluminescence spectroscopy (PL) and active spices trapping experiments. This study provides a promising platform for Z-scheme heterojunction constructing and also sheds light on highly efficient visible-light-driven photocatalysts designing.

An In-Depth Investigation into the Physicochemical, Thermal, Microstructural, and Rheological Properties of Petroleum and Natural Asphalts.

PubMed

Nciri, Nader; Kim, Jeonghyun; Kim, Namho; Cho, Namjun

2016-10-21

Over the last decade, unexpected and sudden pavement failures have occurred in several provinces in South Korea. Some of these failures remain unexplained, further illustrating the gaps in our knowledge about binder chemistry. To prevent premature pavement distress and enhance road performance, it is imperative to provide an adequate characterization of asphalt. For this purpose, the current research aims at inspecting the chemistry, microstructure, thermal, and physico-rheological properties of two types of asphalt, namely petroleum asphalt (PA) and natural asphalt (NA). The binders were extensively investigated by using elemental analysis, thin-layer chromatography with flame ionization detection (TLC-FID), matrix-assisted laser desorption ionization time-of-fight mass spectroscopy (MALDI-TOF-MS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), Nuclear magnetic resonance spectroscopy (¹H-NMR), ultraviolet and visible spectroscopy (UV-VIS), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), penetration, softening point, ductility, and viscosity tests. The findings of this research have revealed the distinct variations between the chemical compositions, microstructures, and thermo-rheological properties of the two asphalts and provided valuable knowledge into the characteristics of the binders. Such insight has been effective in predicting the performance or distress of road pavement. This paper will, therefore, be of immediate interest to materials engineers in state highway agencies and asphalt industries.

An In-Depth Investigation into the Physicochemical, Thermal, Microstructural, and Rheological Properties of Petroleum and Natural Asphalts

PubMed Central

Nciri, Nader; Kim, Jeonghyun; Kim, Namho; Cho, Namjun

2016-01-01

Over the last decade, unexpected and sudden pavement failures have occurred in several provinces in South Korea. Some of these failures remain unexplained, further illustrating the gaps in our knowledge about binder chemistry. To prevent premature pavement distress and enhance road performance, it is imperative to provide an adequate characterization of asphalt. For this purpose, the current research aims at inspecting the chemistry, microstructure, thermal, and physico-rheological properties of two types of asphalt, namely petroleum asphalt (PA) and natural asphalt (NA). The binders were extensively investigated by using elemental analysis, thin-layer chromatography with flame ionization detection (TLC-FID), matrix-assisted laser desorption ionization time-of-fight mass spectroscopy (MALDI-TOF-MS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), Nuclear magnetic resonance spectroscopy (1H-NMR), ultraviolet and visible spectroscopy (UV-VIS), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), penetration, softening point, ductility, and viscosity tests. The findings of this research have revealed the distinct variations between the chemical compositions, microstructures, and thermo-rheological properties of the two asphalts and provided valuable knowledge into the characteristics of the binders. Such insight has been effective in predicting the performance or distress of road pavement. This paper will, therefore, be of immediate interest to materials engineers in state highway agencies and asphalt industries. PMID:28773979

Extracellular synthesis of silver nanoparticles using Bacillus megaterium against malarial and dengue vector (Diptera: Culicidae).

PubMed

Banu, A Najitha; Balasubramanian, C

2015-11-01

Biosynthesis of silver nanoparticles has provoked nowadays and alternative to physical and chemical approaches. In the present study, silver nanoparticles (AgNPs) were synthesized extracellular method using Bacillus megaterium. The AgNPs formations were confirmed initially through color change, and the aliquots were characterized through UV-visible spectrophotometer, followed by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, and Fourier transform infrared (FTIR) spectra. The surface plasmon resonance band was shown at 430 nm in UV-vis spectrophotometer. The bioreduction was categorized through identifying the compounds responsible for the AgNP synthesis, and the functional group present in B. megaterium cell-free culture was scrutinized using FTIR. The topography and morphology of the particles were determined using SEM. In addition, this biosynthesized AgNPs were found to show higher insecticidal efficacy against vector mosquitoes. The LC50 and LC90 were found to be 0.567, 2.260; 0.90, 4.44; 1.349, 8.269; and 1.640, 9.152 and 0.240, 0.955; 0.331, 1.593; 0.494, 2.811; and 0.700, 4.435 with respect to the first, second, third, and fourth instar larvae of Culex quinquefasciatus and Aedes aegypti. All the calculated χ (2) values are highly significant compared with the tabulated value. Therefore, B. megaterium-synthesized silver nanoparticles would be used as a potent larvicidal agent against Cx. quinquefasciatus and Ae. aegypti.

Synthesis, characterization and effect of calcination temperature on phase transformation and photocatalytic activity of Cu,S-codoped TiO 2 nanoparticles

NASA Astrophysics Data System (ADS)

Hamadanian, M.; Reisi-Vanani, A.; Majedi, A.

2010-01-01

A novel copper and sulfur codoped TiO 2 photocatalyst was synthesized by modified sol-gel method using titanium(IV) isopropoxide, CuCl 2·2H 2O and thiourea as precursors. The samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy equipped with energy dispersive X-ray micro-analysis (SEM-EDX), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) analysis. The XRD results showed undoped and Cu,S-codoped TiO 2 nanoparticles only include anatase phase. Effect of calcination temperature showed rutile phase appears in 650 and 700 °C for undoped and 0.1% Cu,S-codoped TiO 2, respectively. The SEM analysis revealed the doping of Cu and S does not leave any change in morphology of the catalyst surface. The increase of copper doping enhanced "red-shift" in the UV-vis absorption spectra. The TEM images confirmed the dopants suppressed the growth of TiO 2 grains. The photocatalytic activity of samples was tested for degradation of methyl orange (MO) solutions. The results showed photocatalytic activity of the catalysts with 0.05% Cu,0.05% S and 0.1% Cu,0.05% S were higher than that of other catalysts under ultraviolet (UV) and visible irradiation, respectively. Because of synergetic effect of S and Cu, the Cu,S-codoped TiO 2 catalyst has higher activity than undoped and Cu or S doped TiO 2 catalysts.

The variation in surface morphology and hardness of human deciduous teeth samples after laser irradiation

NASA Astrophysics Data System (ADS)

Khalid, Arooj; Bashir, Shazia; Akram, Mahreen; Salman Ahmed, Qazi

2017-11-01

The variation in surface morphology and hardness of human deciduous teeth samples has been investigated after laser irradiation at different wavelengths and energies. Nd:YAG was employed as a source of irradiation for IR (1064 nm) and visible (532 nm) radiation, whereas an excimer laser was used as the source of UV (248 nm) radiation. Scanning electron microscope (SEM) analysis was carried out to reveal the surface morphological evolution of teeth samples. Vickers microhardness tester was employed to investigate the modifications in the hardness of the laser-treated samples. It is observed from SEM analysis that IR wavelength is responsible for ablation of collagen matrix and intertubular dentine. For visible radiation, the ablation of collagen along with hydroxypatite is observed. With UV radiation, the ablation of peritubular dentine is dominant and is responsible for the sealing of tubules. The decrease in hardness at lower energy for both wavelengths is due to the evaporation of carbon content. With increasing energy, evaporation of water along with carbon content, and resolidification and re-organization of inorganic content causes the increase in hardness of the treated dentine. SEM as well as microhardness analyses reveal that laser wavelengths and energy of laser radiation significantly influence the surface morphology and hardness of samples.

Monitoring light-induced structural changes of Channelrhodopsin-2 by UV-visible and Fourier transform infrared spectroscopy.

PubMed

Ritter, Eglof; Stehfest, Katja; Berndt, Andre; Hegemann, Peter; Bartl, Franz J

2008-12-12

Channelrhodopsin-2 (ChR2) is a microbial type rhodopsin and a light-gated cation channel that controls phototaxis in Chlamydomonas. We expressed ChR2 in COS-cells, purified it, and subsequently investigated this unusual photoreceptor by flash photolysis and UV-visible and Fourier transform infrared difference spectroscopy. Several transient photoproducts of the wild type ChR2 were identified, and their kinetics and molecular properties were compared with those of the ChR2 mutant E90Q. Based on the spectroscopic data we developed a model of the photocycle comprising six distinguishable intermediates. This photocycle shows similarities to the photocycle of the ChR2-related Channelrhodopsin of Volvox but also displays significant differences. We show that molecular changes include retinal isomerization, changes in hydrogen bonding of carboxylic acids, and large alterations of the protein backbone structure. These alterations are stronger than those observed in the photocycle of other microbial rhodopsins like bacteriorhodopsin and are related to those occurring in animal rhodopsins. UV-visible and Fourier transform infrared difference spectroscopy revealed two late intermediates with different time constants of tau = 6 and 40 s that exist during the recovery of the dark state. The carboxylic side chain of Glu(90) is involved in the slow transition. The molecular changes during the ChR2 photocycle are discussed with respect to other members of the rhodopsin family.

Monitoring Light-induced Structural Changes of Channelrhodopsin-2 by UV-visible and Fourier Transform Infrared Spectroscopy*

PubMed Central

Ritter, Eglof; Stehfest, Katja; Berndt, Andre; Hegemann, Peter; Bartl, Franz J.

2008-01-01

Channelrhodopsin-2 (ChR2) is a microbial type rhodopsin and a light-gated cation channel that controls phototaxis in Chlamydomonas. We expressed ChR2 in COS-cells, purified it, and subsequently investigated this unusual photoreceptor by flash photolysis and UV-visible and Fourier transform infrared difference spectroscopy. Several transient photoproducts of the wild type ChR2 were identified, and their kinetics and molecular properties were compared with those of the ChR2 mutant E90Q. Based on the spectroscopic data we developed a model of the photocycle comprising six distinguishable intermediates. This photocycle shows similarities to the photocycle of the ChR2-related Channelrhodopsin of Volvox but also displays significant differences. We show that molecular changes include retinal isomerization, changes in hydrogen bonding of carboxylic acids, and large alterations of the protein backbone structure. These alterations are stronger than those observed in the photocycle of other microbial rhodopsins like bacteriorhodopsin and are related to those occurring in animal rhodopsins. UV-visible and Fourier transform infrared difference spectroscopy revealed two late intermediates with different time constants of τ = 6 and 40 s that exist during the recovery of the dark state. The carboxylic side chain of Glu90 is involved in the slow transition. The molecular changes during the ChR2 photocycle are discussed with respect to other members of the rhodopsin family. PMID:18927082

Natural fiber templated TiO2 microtubes via a double soaking sol-gel route and their photocatalytic performance

NASA Astrophysics Data System (ADS)

Yang, Li; Li, Xu; Wang, Ziru; Shen, Yun; Liu, Ming

2017-10-01

TiO2 microtubes with a yam-like surface were prepared for the first time through a simple and efficient double soaking sol-gel route by utilizing Platanus acerifolia seed fibers as bio-templates. The physicochemical properties of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), Brunauer Emmett Teller (BET) surface analysis and Ultraviolet-visible absorption spectroscopy (UV-vis). The results showed that the obtained TiO2 microtubes had an anatase phase and were composed of a smooth internal wall and a rough yam-like external wall with an average diameter of 24 μm and the wall thickness of 2 μm. The surface area and pore volume of the as-prepared TiO2 microtubes reached 128.271 m2/g and 0.149 cm3/g, respectively. The UV-vis analysis displayed a favorable extension of light absorption capacity of TiO2 microtubes. The synthetic mechanism was preliminarily discussed as well. The moisture in the natural fiber templates facilitated the mild hydrolysis of titanium sol, leaving a prime layer on the surface of the fibers, and subsequently assisted in the successful preparation of TiO2 microtubes with a yam-like surface without requiring specific control of hydrolysis. Photocatalytic experiments indicated that the as-obtained TiO2 microtubes exhibited a higher efficiency than commercial P25 in the degradation of tetracycline hydrochloride.

Hydrothermal preparation of silver telluride nanostructures and photo-catalytic investigation in degradation of toxic dyes

NASA Astrophysics Data System (ADS)

Gholamrezaei, Sousan; Salavati-Niasari, Masoud; Ghanbari, Davood; Bagheri, Samira

2016-01-01

Different morphologies of Ag2Te nanostructures were synthesized using TeCl4 as a new precursor and hydrazine hydrate as reducing agent by a hydrothermal method. Various parameters that affect on morphology and purity of nanostructures were optimized. According to our experiments the best time and temperature for preparation of this nanostructure are 12 h and 120 °C. The photo-catalytic behaviour of nanostructures in presence of UV- visible light for degradation of methyl orange was investigated. Results show that the presence of UV light is necessary for an efficient degradation of dye in aqueous solution. On the other hand, as observations propose the Ag2Te reveal a strong photoluminescence peak at room temperature that could be attributed to high level transition in the semiconductor. Nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) techniques and UV-visible scanning spectrometer (UV-Vis).

Comparison of carrier transport mechanism under UV/Vis illumination in an AZO photodetector and an AZO/p-Si heterojunction photodiode produced by spray pyrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shasti, M.; Mortezaali, A., E-mail: mortezaali@alzahra.ac.ir; Dariani, R. S.

2015-01-14

In this study, Aluminum doped Zinc Oxide (AZO) layer is deposited on p-type silicon (p-Si) by spray pyrolysis method to fabricate ultraviolet-visible (UV/Vis) photodetector as Al doping process can have positive effect on the photodetector performance. Morphology, crystalline structure, and Al concentration of AZO layer are investigated by SEM, XRD, and EDX. The goal of this study is to analyze the mechanism of carrier transport by means of current-voltage characteristics under UV/Vis illumination in two cases: (a) electrodes connected to the surface of AZO layer and (b) electrodes connected to cross section of heterojunction (AZO/p-Si). Measurements indicate that the AZO/p-Simore » photodiode exhibits a higher photocurrent and lower photoresponse time under visible illumination with respect to AZO photodetector; while under UV illumination, the above result is inversed. Besides, the internal junction field of AZO/p-Si heterojunction plays an important role on this mechanism.« less

Rapid and solvent-free solid-state synthesis and characterization of Zn3V2O8 nanostructures and their phenol red aqueous solution photodegradation

NASA Astrophysics Data System (ADS)

Mazloom, Fatemeh; Masjedi-Arani, Maryam; Salavati-Niasari, Masoud

2017-08-01

Zinc vanadate (Zn3V2O8) nanostructures have been successfully synthesized via simple, rapid and solvent-free solid-state method by using different complex precursors of Zn and NH4VO3 as novel starting materials. Effects of various zinc (II) Schiff base complex precursors and calcination temperatures were investigated to reach optimum condition. It was found that particle size and optical property of the as-prepared products could be greatly influenced via these parameters. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, energy dispersive X-ray microanalysis (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Photoluminescence and ultraviolet-visible (UV-Vis) spectroscopy. The photocatalytic activity of zinc vanadate nano and bulk structures were compared by degradation of phenol red aqueous solution.

Advanced selective non-invasive ketone body detection sensors based on new ionophores

NASA Astrophysics Data System (ADS)

Sathyapalan, A.; Sarswat, P. K.; Zhu, Y.; Free, M. L.

2014-12-01

New molecules and methods were examined that can be used to detect trace level ketone bodies. Diseases such as type 1 diabetes, childhood hypo-glycaemia-growth hormone deficiency, toxic inhalation, and body metabolism changes are linked with ketone bodies concentration. Here we introduce, selective ketone body detection sensors based on small, environmentally friendly organic molecules with Lewis acid additives. Density functional theory (DFT) simulation of the sensor molecules (Bromo-acetonaphthone tungstate (BANT) and acetonaphthophenyl ether propiono hydroxyl tungstate (APPHT)), indicated a fully relaxed geometry without symmetry attributes and specific coordination which enhances ketone bodies sensitivity. A portable sensing unit was made in which detection media containing ketone bodies at low concentration and new molecules show color change in visible light as well as unique irradiance during UV illumination. RGB analysis, electrochemical tests, SEM characterization, FTIR, absorbance and emission spectroscopy were also performed in order to validate the ketone sensitivity of these new molecules.

Temperature-controlled cross-linking of silver nanoparticles with diels-alder reaction and its application on antibacterial property

NASA Astrophysics Data System (ADS)

Liu, Lian; Yang, Pengfei; Li, Junying; Zhang, Zhiliang; Yu, Xi; Lu, Ling

2017-05-01

Sliver nanoparticles (AgNPs) were synthesized and functionalized with furan group on their surface, followed by the reverse Diels-Alder (DA) reaction with bismaleimide to vary the particle size, so as to give different antibacterial activities. These nanoparticles were characterized using Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Ultraviolet-Visible (UV-vis), Nanoparticle Size Analyzer and X-Ray Photoelectron Spectroscopy (XPS). It was found that the cross-linking reaction with bismaleimide had a great effect on the size of AgNPs. The size of the AgNPs could be controlled by the temperature of DA/r-DA equilibrium. The antibacterial activity was assessed using the inhibition zone diameter by introducing the particles into a media containing Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus, respectively. It was found that these particles were effective bactericides. Furthermore, the antibacterial activity of the nanoparticles decreased orderly as the particle size enlarged.

Non-invasive toluene sensor for early diagnosis of lung cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saxena, Rahul; Srivastava, Sudha, E-mail: sudha.srivastava@jiit.ac.in

Here we present, quantification of volatile organic compounds in human breath for early detection of lung cancer to increase survival probability. Graphene oxide nanosheets synthesized by modified Hummer’s method were employed as a sensing element to detect the presence of toluene in the sample. Optical and morphological characterization of synthesized nanomaterial was performed by UV-Visible spectroscopy and scanning electron microscopy (SEM) respectively. Spectroscopic assay shows a linearly decreasing intensity of GO absorption peak with increasing toluene concentration with a linear range from 0-200 pM. While impedimetric sensor developed on a graphene oxide nanosheetsmodified screen printed electrodes displayed a decreasing electronmore » transfer resistance increasing toluene with much larger linear range of 0-1000 pM. Reported techniques are advantageous as these are simple, sensitive and cost effective, which can easily be extended for primary screening of other VOCs.« less

A sulphonated carbon dot-chitosan hybrid hydrogel nanocomposite as an efficient ion-exchange film for Ca2+ and Mg2+ removal

NASA Astrophysics Data System (ADS)

Baruah, Upama; Konwar, Achyut; Chowdhury, Devasish

2016-04-01

We have developed a hybrid hydrogel nanocomposite film via conjugation of oxidised carbon dots synthesized from 11-mercaptoundecanoic acid with chitosan. The potential applicability of the film was then successfully tested for the removal of Ca2+ and Mg2+ ions from solution.We have developed a hybrid hydrogel nanocomposite film via conjugation of oxidised carbon dots synthesized from 11-mercaptoundecanoic acid with chitosan. The potential applicability of the film was then successfully tested for the removal of Ca2+ and Mg2+ ions from solution. Electronic supplementary information (ESI) available: The ESI includes the detailed synthesis and characterization of carbon dots both before and after oxidation and of the carbon dot-chitosan nanocomposite films viz. DLS, SEM, UV-visible, FTIR, PL spectroscopy and TGA. See DOI: 10.1039/c6nr01129b

Fabricate heterojunction diode by using the modified spray pyrolysis method to deposit nickel-lithium oxide on indium tin oxide substrate.

PubMed

Wu, Chia-Ching; Yang, Cheng-Fu

2013-06-12

P-type lithium-doped nickel oxide (p-LNiO) thin films were deposited on an n-type indium tin oxide (ITO) glass substrate using the modified spray pyrolysis method (SPM), to fabricate a transparent p-n heterojunction diode. The structural, optical, and electrical properties of the p-LNiO and ITO thin films and the p-LNiO/n-ITO heterojunction diode were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), UV-visible spectroscopy, Hall effect measurement, and current-voltage (I-V) measurements. The nonlinear and rectifying I-V properties confirmed that a heterojunction diode characteristic was successfully formed in the p-LNiO/n-ITO (p-n) structure. The I-V characteristic was dominated by space-charge-limited current (SCLC), and the Anderson model demonstrated that band alignment existed in the p-LNiO/n-ITO heterojunction diode.

Synthesis and structural characterization of CdS nanoparticles using nitrogen adducts of mixed diisopropylthiourea and dithiolate derivatives of Cd(II) complexes

NASA Astrophysics Data System (ADS)

Osuntokun, Jejenija; Ajibade, Peter A.

2015-07-01

[Cd(diptu)2(ced)], [Cd(diptu)2(ced)(bpy)], [Cd(diptu)2(ced)(phen)], (where diptu = diisopropyl thiourea; ced = 1-cyano-1-carboethoxylethylene-2,2‧-dithiolate; bpy = 2,2‧-bipyridine and phen = 1,10-phenanthroline) have been prepared and used as single source precursors for the preparation of hexadecylamine capped CdS nanoparticles. The precursor complexes were characterized by elemental analysis, FTIR and TGA. The structural properties of the nanoparticles were investigated using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy techniques (SEM). The optical properties of the nanoparticles were studied using UV-Visible and photoluminescence spectroscopy. The XRD analysis showed that the nanoparticles were indexed to the hexagonal phase of CdS and the TEM results showed CdS nanoparticles with average crystallite sizes of 4.00-8.80 nm.

Biopolymer stabilized water dispersible polyaniline for supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Anbalagan, Amarnath Chellachamy; Sawant, Shilpa Nandkishor

2018-04-01

Polyaniline colloidal nanoparticles (PANI CNs) were synthesized, employing biopolymer pectin (Pec) as a stabilizer along with hydrochloric acid dopant and ammonium persulfate oxidant. Chemical nature and electronic structure was studied by FT-IR and UV-visible spectroscopy respectively. FE-SEM revealed spindle like morphology of PANI CNs and displayed the nearly discrete particles without aggregation, showing stabilizing capacity of the Pec. Cyclic voltammetry and galvanostatic charge-discharge measurements demonstrated the electroactivity and supercapacitive property of the PANI CNs in 1 M HCl. The specific capacitance of PANI CNs in 1 M HCl at 1.5 A/g was found to be 197 F/g, where 70% of specific capacitance was retained even after 1000 cycles. These findings establish the feasibility of using the PANI CNs as a potential material for energy storage in aqueous acidic medium. Furthermore, this colloidal dispersion can find potential application in electrodes of flexible supercapacitor device and printable electronics.

Synthesis of Silver nanoparticles (AgNPs) with Antibacterial Activity

NASA Astrophysics Data System (ADS)

Campillo Gloria, E.; Ederley, Vélez; Gladis, Morales; César, Hincapié; Jaime, Osorio; Oscar, Arnache; Uribe José, Ignacio; Franklin, Jaramillo

2017-06-01

The synthesis of nanomaterials is currently one of the most active in nanoscience branches; especially those help improve the human quality life. Silver nanoparticles (AgNPs) are an example of this as it is known to have inhibitory and bactericidal effects. In this work, we report the synthesis of silver nanoparticles by chemical reduction method of silver nitrate (AgNO3) from aqueous solution, using a mix of polivinyl pyrrolidone (PVP) - Aloe Vera as reducing agent and for stabilization and control of particle size. Silver nanoparticles obtained were characterized by Scanning Electron Microscopy (SEM), UV-visible spectroscopy and measurements using Zetasizer Nano ZS were applied to size estimation. The existence of surface plasmon resonance peak at λmax ~ 420 nm is evidence of silver nanoparticles formation. It was possible to standardize an appropriate protocol for the evaluation of bactericidal activity of the nanoparticles, for mesophilic microorganisms. Bactericidal activity above 90% against these kinds of bacteria was demonstrated.

Utilization of granular activated carbon adsorber for nitrates removal from groundwater of the Cluj region.

PubMed

Moşneag, Silvia C; Popescu, Violeta; Dinescu, Adrian; Borodi, George

2013-01-01

The level of nitrates from groundwater from Cluj County and other areas from Romania have increased values, exceeding or getting close to the allowed limit values, putting in danger human and animal heath. In this study we used granular activated carbon adsorbent (GAC) for nitrate (NO(-)3) removal for the production of drinking water from groundwater of the Cluj county. The influences of the contact time, nitrate initial concentration, and adsorbent concentration have been studied. We determined the equilibrium adsorption capacity of GAC, used for NO(-)3 removal and we applied the Langmuir and Freundlich isotherm models. Ultraviolet-visible (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy, X ray diffraction (XRD), Scanning Electron Microscopy (SEM) were used for process characterization. We also determined: pH, conductivity, Total Dissolved Solids and Total Hardness. The GAC adsorbents have excellent capacities of removing nitrate from groundwater from Cluj County areas.

Biofilm Formation by Pseudomonas Species Onto Graphene Oxide-TiO2 Nanocomposite-Coated Catheters: In vitro Analysis

NASA Astrophysics Data System (ADS)

Deb, Ananya; Vimala, R.

The present study focuses on the development of an in vitro model system for biofilm growth by Pseudomonas aerouginosa onto small discs of foley catheter. Catheter disc used for the study was coated with graphene oxide-titanium oxide composite (GO-TiO2) and titanium oxide (TiO2) and characterized through XRD, UV-visible spectroscopy. Morphological analysis was done by scanning electron microscopy (SEM). The biofilm formed on the catheter surface was quantified by crystal violet (CV) staining method and a colorimetric assay (MTT assay) which involves the reduction of tetrazolium salt. The catheter coated with GO-TiO2 showed reduced biofilm growth in comparison to the TiO2-coated and uncoated catheter, thus indicating that it could be successfully used in coating biomedical devices to prevent biofilm formation which is a major cause of nosocomial infection.

Large-scale preparation of strawberry-like, AgNP-doped SiO2 microspheres using the electrospraying method

NASA Astrophysics Data System (ADS)

Ma, Zhijun; Ji, Huijiao; Tan, Dezhi; Dong, Guoping; Teng, Yu; Zhou, Jiajia; Guan, Miaojia; Qiu, Jianrong; Zhang, Ming

2011-07-01

In this paper, we report on a novel strategy for the preparation of silver nanoparticle-doped SiO2 microspheres (Ag-SMSs) with an interesting strawberry-like morphology using a simple and efficient electrospraying method. SEM (scanning electron microscopy), TEM (transmission electron microscopy), XRD (x-ray diffraction), EDS (energy-dispersive spectroscopy) and UV-vis spectra (ultraviolet-visible spectra) were applied to investigate the morphology, structure, composition and optical properties of the hybrid microspheres, and E. coli (Escherichia coli) was used as a model microbe to evaluate their antibacterial ability. The results showed that the Ag-SMSs were environmentally stable and washing resistant. The Ag-SMSs exhibited effective inhibition against proliferation of E. coli, and their antibacterial ability could be well preserved for a long time. The environmental stability, washing resistance, efficient antibacterial ability and simple but productive preparation method endowed the Ag-SMSs with great potential for practical biomedical applications.

Investigation of photocalalytic activity of ZnO prepared by spray pyrolis with various precursors

NASA Astrophysics Data System (ADS)

Bourfaa, F.; Lamri Zeggar, M.; A, A.; Aida, M. S.; Attaf, N.

2016-03-01

Semiconductor photocatalysts such as ZnO has attracted much attention in recent years due to their various applications for the degradation of organic pollutants in water, air and in dye sensitized photovoltaic solar cell. In the present work, ZnO thin films were prepared by ultrasonic spray pyrolysis by using different precursors namely: acetate, chloride and zinc nitrate in order to investigate their influence on ZnO photocatalytic activity. The films crystalline structure was studied by mean of X- ray diffraction measurements (XRD) and the films surface morphology by Scanning Electron Microscopy (SEM). The films optical properties were studied by mean of UV-visible spectroscopy. The prepared films were tested for the degradation of the red reactive dye largely used in textile industry. As a result, we found that the zinc nitrate is the best precursor to prepare ZnO thin films suitable for a good photocatalytic activity.

Boehmite-An Efficient and Recyclable Acid-Base Bifunctional Catalyst for Aldol Condensation Reaction.

PubMed

Reshma, P C Rajan; Vikneshvaran, Sekar; Velmathi, Sivan

2018-06-01

In this work boehmite was used as an acid-base bifunctional catalyst for aldol condensation reactions of aromatic aldehydes and ketones. The catalyst was prepared by simple sol-gel method using Al(NO3)3·9H2O and NH4OH as precursors. The catalyst has been characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), UV-visible spectroscopy (DRS), BET surface area analyses. Boehmite is successfully applied as catalyst for the condensation reaction between 4-nitrobenzaldehyde and acetone as a model substrate giving α, β-unsaturated ketones without any side product. The scope of the reaction is extended for various substituted aldehydes. A probable mechanism has been suggested to explain the cooperative behavior of the acidic and basic sites. The catalyst is environmentally friendly and easily recovered from the reaction mixture. Also the catalyst is reusable up to 3 catalytic cycles.

Thermal Conductivity on the Nanofluid of Graphene and Silver Nanoparticles Composite Material.

PubMed

Myekhlai, Munkhshur; Lee, Taejin; Baatar, Battsengel; Chung, Hanshik; Jeong, Hyomin

2016-02-01

The composite material consisted of graphene (GN) and silver nanoparticles (AgNPs) has been essential topic in science and industry due to its unique thermal, electrical and antibacterial proper- ties. However, there are scarcity studies based on their thermal properties of nanofluids. Therefore, GN-AgNPs composite material was synthesized using facile and environment friendly method and further nanofluids were prepared by ultrasonication in this study. The morphological and structural investigations were carried out using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD) as well as ultra violet (UV)-visible spectroscopy. Furthermore, thermal conductivity measurements were performed for as-prepared nanofluids. As a result of thermal conductivity study, GN-AgNPs composite material was considerably enhanced the thermal conductivity of base fluid (water) by to 6.59% for the nanofluid (0.2 wt% GN and 0.4 wt% AgNPs).

Demonstrating Basic Properties of Spectroscopy Using a Self-Constructed Combined Fluorimeter and UV-Photometer

ERIC Educational Resources Information Center

Kvittingen, Eivind V.; Kvittingen, Lise; Melø, Thor Bernt; Sjursnes, Birte Johanne; Verley, Richard

2017-01-01

This article describes a combined UV-photometer and fluorimeter constructed from 3 LEDs and a few wires, all held in place with Lego bricks. The instrument has a flexible design. In its simplest version, two UV-LEDs (355 nm) are used as light source and to detect absorption, and a third LED, in the visible spectrum (e.g., 525 nm), is used to…

UV-Visible Absorption Spectroscopy Enhanced X-ray Crystallography at Synchrotron and X-ray Free Electron Laser Sources.

PubMed

Cohen, Aina E; Doukov, Tzanko; Soltis, Michael S

2016-01-01

This review describes the use of single crystal UV-Visible Absorption micro-Spectrophotometry (UV-Vis AS) to enhance the design and execution of X-ray crystallography experiments for structural investigations of reaction intermediates of redox active and photosensitive proteins. Considerations for UV-Vis AS measurements at the synchrotron and associated instrumentation are described. UV-Vis AS is useful to verify the intermediate state of an enzyme and to monitor the progression of reactions within crystals. Radiation induced redox changes within protein crystals may be monitored to devise effective diffraction data collection strategies. An overview of the specific effects of radiation damage on macromolecular crystals is presented along with data collection strategies that minimize these effects by combining data from multiple crystals used at the synchrotron and with the X-ray free electron laser.

Influence of rare earth ions on microstructural and optical properties of ZnO nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riyajuddin, Sk., E-mail: riyaj5303@gmail.com; Ahmad, Shabbir; Faizan, M.

2016-05-23

Pure and 3% rare earth ions (Nd{sup 3+} & Gd{sup 3+}) doped ZnO samples were synthesized by sol-gel method, followed by annealing at temperature 450°C for 2hr. The samples were characterized by XRD, FTIR and UV-visible spectroscopy. XRD result confirmed single phase nature of all samples with crystalline structure. The average crystallite size of the doped samples found to be decreases as caculated using Debye-Scherrer’s formula. FTIR spectra indicate absorption band centered at 464 cm{sup −1} which is attributed to Zn-O lattice vibration. It confirms the formaton of compounds. UV-visible spectroscopy was used to study the optical properties and band gapmore » of the synthesised materials using Tauc’s relation.« less

Synthesis of Silver Polymer Nanocomposites and Their Antibacterial Activity

NASA Astrophysics Data System (ADS)

Gavade, Chaitali; Shah, Sunil; Singh, N. L.

2011-07-01

PVA (Polyvinyl Alcohol) silver nanocomposites of different sizes were prepared by chemical reduction method. Silver nitrate was taken as the metal precursor and amine hydrazine as a reducing agent. The formation of the silver nanoparticles was noticed using UV- visible absorption spectroscopy. The UV-visible spectroscopy revealed the formation of silver nanoparticles by exhibiting the surface plasmon resonance. The bactericidal activity due to silver release from the surface was determined by the modification of conventional diffusion method. Salmonella typhimurium, Serratia sps and Shigella sps were used as test bacteria which are gram-negative type bacteria. Effect of the different sizes of silver nano particles on antibacterial efficiency was discussed. Zones of inhibition were measured after 24 hours of incubation at 37 °C which gave 20 mm radius for high concentration of silver nanoparticles.

Rapid extra-/intracellular biosynthesis of gold nanoparticles by the fungus Penicillium sp.

NASA Astrophysics Data System (ADS)

Du, Liangwei; Xian, Liang; Feng, Jia-Xun

2011-03-01

In this work, the fungus Penicillium was used for rapid extra-/intracellular biosynthesis of gold nanoparticles. AuCl4 - ions reacted with the cell filtrate of Penicillium sp. resulting in extracellular biosynthesis of gold nanoparticles within 1 min. Intracellular biosynthesis of gold nanoparticles was obtained by incubating AuCl4 - solution with fungal biomass for 8 h. The gold nanoparticles were characterized by means of visual observation, UV-Vis absorption spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The extracellular nanoparticles exhibited maximum absorbance at 545 nm in UV-Vis spectroscopy. The XRD spectrum showed Bragg reflections corresponding to the gold nanocrystals. TEM exhibited the formed spherical gold nanoparticles in the size range from 30 to 50 nm with an average size of 45 nm. SEM and TEM revealed that the intracellular gold nanoparticles were well dispersed on the cell wall and within the cell, and they are mostly spherical in shape with an average diameter of 50 nm. The presence of gold was confirmed by EDX analysis.

Synthesis and characterization of CdS-based ternary composite for enhanced visible light-driven photocatalysis

NASA Astrophysics Data System (ADS)

Singh, Arvind; Sinha, A. S. K.

2018-09-01

Active ternary graphite and alumina-supported cadmium sulphide (CdS) composite was synthesized by impregnation method followed by high-temperature solid-gas reaction and characterized by X-ray diffraction (XRD), photoluminescence spectroscopy (PL), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) techniques. The ternary CdS-graphite-alumina composite exhibited superior catalytic activity compared with the binary CdS-alumina composite due to its better visible-light absorption and higher charge separation. The ternary composite has a bed-type structure. It permits a greater interaction at the interface due to intimate contact between CdS and graphite in the ternary composite. This composite has a highly efficient visible light-driven photocatalytic activity for sustainable hydrogen production. It is also capable of degrading organic dyes in wastewater.

Structural and electrical properties of CZTS thin films by electrodeposition

NASA Astrophysics Data System (ADS)

Rao, M. C.; Basha, Sk. Shahenoor

2018-06-01

CZTS (Cu2ZnSnS4) thin films were coated on ITO glass substrates by single bath electrodeposition technique. The prepared films were subsequently characterized by XRD, SEM, FTIR, UV-visible spectroscopy and Raman studies. The thickness of the thin films was measured by wedge method. X-ray diffraction studies revealed the formation of polycrystalline phase. The morphological surface of the prepared thin films was examined by SEM and AFM and showed the presence of microcrystals on the surface of the samples. The elemental analysis and their compositional ratios present in the samples were confirmed by the energy dispersive X-ray analysis. Functional groups and the position of band structure involved in the materials were confirmed by FTIR. Optical absorption studies were performed on the prepared thin films in the wavelength ranging from 300 to 1000 nm and the energy bandgap values were found to be in the range from 1.39 to 1.60 eV. Raman spectral peak which was observed at 360 cm-1 correspond to kesterite phase, was formed due to the vibration of the molecules. Electrical measurements confirmed the nature of the thin film depending on the charge concentration present in the samples.

Influence of a novel co-doping (Zn + F) on the physical properties of nano structured (1 1 1) oriented CdO thin films applicable for window layer of solar cell

NASA Astrophysics Data System (ADS)

Anitha, M.; Saravanakumar, K.; Anitha, N.; Amalraj, L.

2018-06-01

Un-doped and co-doped (Zn + F) cadmium oxide (CdO) thin films were prepared by modified spray pyrolysis technique using a nebulizer on glass substrates kept at 200 °C. They were characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), UV-vis spectroscopy, Hall Effect and photoluminescence (PL) respectively. The thin films were having thickness in the range of 520-560 nm. They were well crystalline and displayed high transparency of about >70% in the visible region. It was clearly seen from the SEM photographs that co-doping causes notable changes in the surface morphology. Electrical study exhibited the resistivity of co-doped CdO thin films drastically fell to 1.43 × 10-4 Ω-cm compared with the un-doped CdO thin film. The obtained PL spectra were well corroborated with the structural and optical studies. The high transparency, wide band gap energy and enhanced electrical properties obtained infer that Zn + F co-doped CdO thin films find application in optoelectronic devices, especially in window layer of solar cells.

Transformation of toxic and allelopathic lantana into a benign organic fertilizer through vermicomposting

NASA Astrophysics Data System (ADS)

Hussain, Naseer; Abbasi, Tasneem; Abbasi, S. A.

2016-06-01

In a first study of its kind, the composition of vermicompost derived solely from the toxic and allelopathic weed lantana has been investigated using UV-visible and Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric (TG) and differential scanning calorimetry (DSC), gas chromatography-mass spectometry (GC-MS), and scanning electron microscopy (SEM). The studies reveal that a sharp reduction in humification index, substantial mineralization of organic matter and degradation of complex aromatics such as lignin and polyphenols into simpler carbohydrates and lipids occur in the course of vermicomposting. GC-MS analysis shows significant fragmentation, bio-oxidation and molecular rearrangements of chemical compounds in vermicompost in comparison to those in lantana. SEM micrographs of vermicompost reflect strong disaggregation of material compared to the much better formed lantana matrices. The phenols and sesquiterpene lactones which are specifically responsible for the toxicity and allelopathy of lantana are seen to get significantly degraded in the course of vermicomposting - turning it into a plant-friendly organic fertilizer. The study leads to the possibility that the millions of tons of phytomass that is generated annually by lantana can be gainfully utilized in producing organic fertilizer via vermicomposting.

Synthesis and photocatalytic activity of N-doped TiO2 produced in a solid phase reaction

NASA Astrophysics Data System (ADS)

Xin, Gang; Pan, Hongfei; Chen, Dan; Zhang, Zhihua; Wen, Bin

2013-02-01

N-doped TiO2 was synthesized by calcining a mixture of titanic acid and graphitic carbon nitride (g-C3N4) at temperatures above 500 °C. The final samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and UV-vis diffuse reflectance spectra. The photocatalytic activity of N-doped TiO2 was studied by assessing the degradation of methylene blue in an aqueous solution, under visible light and UV light irradiation. It was found that the N-doped TiO2 displayed higher photocatalytic activity than pure TiO2, under both visible and UV light.

Interaction of flavonoids, the naturally occurring antioxidants with different media: A UV-visible spectroscopic study

NASA Astrophysics Data System (ADS)

Naseem, Bushra; Shah, S. W. H.; Hasan, Aurangzeb; Sakhawat Shah, S.

2010-04-01

Quantitative parameters for interaction of flavonoids—the naturally occurring antioxidants, with solvents and surfactants are determined using UV-visible absorption spectroscopy. The availability of flavonoids; kaempferol, apigenin, kaempferide and rhamnetin in micelles of sodium dodecyl sulfate (SDS) is reflected in terms of partition coefficient, Kc. Thermodynamic calculations show that the process of transfer of flavonoid molecules to anionic micelles of SDS is energy efficient. A distortion in flavonoid's morphology occurs in case of kaempferol and apigenin in surfactant and water, exhibited in terms of a new band in the UV region of electronic spectra of these flavonoids. The partition coefficients of structurally related flavonoids are correlated with their antioxidant activities.

Characterisation of PDO olive oil Chianti Classico by non-selective (UV-visible, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques.

PubMed

Casale, M; Oliveri, P; Casolino, C; Sinelli, N; Zunin, P; Armanino, C; Forina, M; Lanteri, S

2012-01-27

An authentication study of the Italian PDO (protected designation of origin) extra virgin olive oil Chianti Classico was performed; UV-visible (UV-vis), Near-Infrared (NIR) and Mid-Infrared (MIR) spectroscopies were applied to a set of samples representative of the whole Chianti Classico production area. The non-selective signals (fingerprints) provided by the three spectroscopic techniques were utilised both individually and jointly, after fusion of the respective profile vectors, in order to build a model for the Chianti Classico PDO olive oil. Moreover, these results were compared with those obtained by the gas chromatographic determination of the fatty acids composition. In order to characterise the olive oils produced in the Chianti Classico PDO area, UNEQ (unequal class models) and SIMCA (soft independent modelling of class analogy) were employed both on the MIR, NIR and UV-vis spectra, individually and jointly, and on the fatty acid composition. Finally, PLS (partial least square) regression was applied on the UV-vis, NIR and MIR spectra, in order to predict the content of oleic and linoleic acids in the extra virgin olive oils. UNEQ, SIMCA and PLS were performed after selection of the relevant predictors, in order to increase the efficiency of both classification and regression models. The non-selective information obtained from UV-vis, NIR and MIR spectroscopy allowed to build reliable models for checking the authenticity of the Italian PDO extra virgin olive oil Chianti Classico. Copyright © 2011 Elsevier B.V. All rights reserved.

Photocatalytic degradation of p,p'-DDT under UV and visible light using interstitial N-doped TiO₂.

PubMed

Ananpattarachai, Jirapat; Kajitvichyanukul, Puangrat

2015-01-01

1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (or p,p'-DDT) is one of the most persistent pesticides. It is resistant to breakdown in nature and cause the water contamination problem. In this work, a major objective was to demonstrate the application of N-doped TiO2 in degradation and mineralization of the p,p'-DDT under UV and visible light in aqueous solution. The N-doped TiO2 nanopowders were prepared by a simple modified sol-gel procedure using diethanolamine (DEA) as a nitrogen source. The catalyst characteristics were investigated using XRD, SEM, TEM, and XPS. The adsorption and photocatalytic oxidation of p,p'-DDT using the synthesized N-doped TiO2 under UV and visible light were conducted in a batch photocatalytic experiment. The kinetics and p,p'-DDT degradation performance of the N-doped TiO2 were evaluated. Results show that the N-doped TiO2 can degrade p,p'-DDT effectively under both UV and visible lights. The rate constant of the p,p'-DDT degradation under UV light was only 0.0121 min(-1), whereas the rate constant of the p,p'-DDT degradation under visible light was 0.1282 min(-1). Under visible light, the 100% degradation of p,p'-DDT were obtained from N-doped TiO2 catalyst. The reaction rate of p,p'-DDT degradation using N-doped TiO2 under visible light was sixfold higher than that under UV light. According to Langmuir-Hinshelwood model, the adsorption equilibrium constant (K) for the N-doped TiO2 under visible light was 0.03078 L mg(-1), and the apparent reaction rate constant (k) was 1.3941 mg L(-1)-min. Major intermediates detected during the p,p'-DDT degradation were p,p'-DDE, o,p'-DDE, p,p'-DDD and p,p'-DDD. Results from this work can be applied further for the breakdown of p,p'-DDT molecule in the real contaminated water using this technology.

Impact of nanostructured thin ZnO film in ultraviolet protection

PubMed Central

Sasani Ghamsari, Morteza; Alamdari, Sanaz; Han, Wooje; Park, Hyung-Ho

2017-01-01

Nanoscale ZnO is one of the best choices for ultraviolet (UV) protection, not only because of its antimicrobial properties but also due to its potential application for UV preservation. However, the behavior of nanostructured thin ZnO films and long-term effects of UV-radiation exposure have not been studied yet. In this study, we investigated the UV-protection ability of sol gel-derived thin ZnO films after different exposure times. Scanning electron microscopy, atomic force microscopy, and UV-visible optical spectroscopy were carried out to study the structure and optical properties of the ZnO films as a function of the UV-irradiation time. The results obtained showed that the prepared thin ZnO films were somewhat transparent under the visible wavelength region and protective against UV radiation. The UV-protection factor was 50+ for the prepared samples, indicating that they were excellent UV protectors. The deposited thin ZnO films demonstrated promising antibacterial potential and significant light absorbance in the UV range. The experimental results suggest that the synthesized samples have potential for applications in the health care field. PMID:28096668

Impact of nanostructured thin ZnO film in ultraviolet protection.

PubMed

Sasani Ghamsari, Morteza; Alamdari, Sanaz; Han, Wooje; Park, Hyung-Ho

2017-01-01

Nanoscale ZnO is one of the best choices for ultraviolet (UV) protection, not only because of its antimicrobial properties but also due to its potential application for UV preservation. However, the behavior of nanostructured thin ZnO films and long-term effects of UV-radiation exposure have not been studied yet. In this study, we investigated the UV-protection ability of sol gel-derived thin ZnO films after different exposure times. Scanning electron microscopy, atomic force microscopy, and UV-visible optical spectroscopy were carried out to study the structure and optical properties of the ZnO films as a function of the UV-irradiation time. The results obtained showed that the prepared thin ZnO films were somewhat transparent under the visible wavelength region and protective against UV radiation. The UV-protection factor was 50+ for the prepared samples, indicating that they were excellent UV protectors. The deposited thin ZnO films demonstrated promising antibacterial potential and significant light absorbance in the UV range. The experimental results suggest that the synthesized samples have potential for applications in the health care field.

Charge Carrier Dynamics and pH Effect on Optical Properties of Anionic and Cationic Porphyrin-Graphene Oxide Composites

NASA Astrophysics Data System (ADS)

Bajjou, O.; Bakour, A.; Khenfouch, M.; Baitoul, M.; Mothudi, B.; Maaza, M.; Faulques, E.

2018-02-01

Composites of graphene oxide (GO) functionalized with Sn(V) tetrakis (4-pyridyl)porphyrin (SnTPyP2+) and meso-tetrakis(4-phenylsulfonic acid)porphyrin (H4TPPS4 2- ) were prepared at different pH values.Successful synthesis of water-soluble stable suspension of GO-SnTPyP2+ and GO-H4TPPS4 2-was confirmed using various spectroscopic techniques, including scanning electronic microscopy (SEM), Raman spectroscopy, and ultraviolet-visible (UV-Vis) absorption. Variation of the pH was found to strongly influence the optical properties of the GO-SnTPyP2+ and GO-H4TPPS4 2-composites, as demonstrated by the UV-Vis absorption results. Steady-state photoluminescence (PL) and time-resolved PL (TRPL) results for both composites showed PL quenching and decrease in the exciton mean lifetime, suggesting strong excited-state interactions between the different components. Moreover, charge carrier dynamics study revealed that insertion of GO into both porphyrin derivatives led to faster mean lifetime for excitons with a slight advantage in the case of the cationic porphyrin-GO composite, making it a better choice for charge separation applications thanks to the higher efficiency of charge/energy transfer interactions.

Tunable emission in surface passivated Mn-ZnS nanophosphors and its application for Glucose sensing

NASA Astrophysics Data System (ADS)

Sharma, Manoj; Jain, Tarun; Singh, Sukhvir; Pandey, O. P.

2012-03-01

The present work describes the tunable emission in inorganic-organic hybrid NPs which can be useful for optoelectronic and biosensing applications. In this work, Mn- ZnS nanoparticles emitting various colors, including blue and orange, were synthesized by simple chemical precipitation method using chitosan as a capping agent. Earlier reports describe that emission color characteristics in nanoparticles are tuned by varying particle size and with doping concentration. Here in this article tunable emission has been achieved by varying excitation wavelength in a single sample. This tunable emission property with high emission intensity was further achieved by changing capping concentration keeping host Mn-ZnS concentration same. Tunable emission is explained by FRET mechanism. Commission Internationale de l'Eclairage (CIE) chromaticity coordinates shifts from (0.273, 0.20) and (0.344, 0.275) for same naocrystals by suitably tuning excitation energy from higher and lower ultra-violet (UV) range. Synthesized nanoparticles have been characterized by X-ray diffraction, SEM, HRTEM, UV- Visible absorption and PL spectroscopy for structural and optical studies. Using tunable emission property, these highly emissive nanoparticles functionalized with biocompatible polymer chitosan were further used for glucose sensing applications.

Morphology, structure and optical properties of hydrothermally synthesized CeO2/CdS nanocomposites

NASA Astrophysics Data System (ADS)

Mohanty, Biswajyoti; Nayak, J.

2018-04-01

CeO2/CdS nanocomposites were synthesized using a two-step hydrothermal technique. The effects of precursor concentration on the optical and structural properties of the CeO2/CdS nanoparticles were systematically studied. The morphology, composition and the structure of the CeO2/CdS nanocomposite powder were studied by scanning electron microscopy (SEM), energy dispersive X-ray spectrum analysis (EDXA) and X-ray diffraction (XRD), respectively. The optical properties of CeO2/CdS nanocomposites were studied by UV-vis absorption and photoluminescence (PL) spectroscopy. The optical band gaps of the CeO2/CdS nanopowders ranged from 2.34 eV to 2.39 eV as estimated from the UV-vis absorption. In the room temperature photoluminescence spectrum of CeO2/CdS nanopowder, a strong blue emission band was observed at 400 nm. Since the powder shows strong visible luminescence, it may be used as a blue phosphor in future. The original article published with this DOI was submitted in error. The correct article was inadvertently left out of the original submission. This has been rectified and the correct article was published online on 16 April 2018.

Chromatographic analysis of phytochemicals components present in mangifera indica leaves for the synthesis of silver nanoparticles by AgNO3 reduction

NASA Astrophysics Data System (ADS)

Martínez-Bernett, D.; Silva-Granados, A.; Correa-Torres, S. N.; Herrera, A.

2016-02-01

It was studied the green synthesis of silver nanoparticles (AgNPs) from the reduction of a silver nitrate solution (1 and 10mM) in the presence of an extract of mangifera indica leaves. Phytochemicals components present in extracts of mango leaves were determined using a GC-MS chromatograph. The results showed the presence of the phenolic compound pyrogallol (26.9% wt/5mL of extract) and oleic acid (29.1% wt/5mL of extract), which are useful for the reduction of the metallic salt AgNO3 and the stabilization of silver nanoparticles. The synthesized nanoparticles were characterized by UV visible spectroscopy (UV-vis), evidencing absorbances at wavelengths of 417nm (AgNPs-1) and 414nm (AgNPs- 10), which are characteristic peaks of this metallic nanoparticles. Scanning Electron Microscopy (SEM) was used to determine the size of the synthesized nanoparticles. A particle size of about 28±7nm was observed for the AgNPs-1 sample and 26±5nm for the AgNPs-10. This suggests the advantages of green chemistry to obtain silver nanoparticles with a narrow size distribution.

Synthesis and characterization of nano TiO2-SiO2: PVA composite - a novel route

NASA Astrophysics Data System (ADS)

Venckatesh, Rajendran; Balachandaran, Kartha; Sivaraj, Rajeshwari

2012-07-01

A novel, simple, less time consuming and cost-effective sol-gel method has been developed to synthesize nano titania-silica with polyvinyl alcohol (PVA) composite relatively at low temperature in acidic pH. Titania sol is prepared by hydrolysis of titanium tetrachloride and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6 h and dried at room temperature with the addition of PVA solution. The resulting powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared (FT-IR), UV-visible spectroscopy and thermal techniques. The grain size of the particles was calculated by X-ray diffraction; surface morphology and chemical composition were determined from scanning electron microscopy-energy dispersive spectroscopy; metal oxide stretching was confirmed from FT-IR spectroscopy; bandgap was calculated using UV-visible spectroscopy, and thermal stability of the prepared composite was determined by thermogravimetric/differential thermal analysis. Since TiO2 got agglomerated on the surface of SiO2, effective absorptive sites increase which in turn increase the photocatalytic efficiency of the resulting composite.

Controlling the Optical and Magnetic Properties of Nanostructured Cuprous Oxide Synthesized from Waste Electric Cables

NASA Astrophysics Data System (ADS)

Abdelbasir, S. M.; El-Sheikh, S. M.; Rashad, M. M.; Rayan, D. A.

2018-03-01

Cuprous oxide Cu2O nanopowders were purposefully synthesised from waste electric cables (WECs) via a simple precipitation route at room temperature using lactose as a reducing agent. In this regard, dimethyl sulfoxide (DMSO) was first applied as an organic solvent for the dissolution of the cable insulating materials. Several parameters were investigated during dissolution of WECs such as dissolution temperature, time and solid/liquid ratio to determine the dissolution percentage of the insulating materials in DMSO. The morphology and the optical properties of the formed Cu2O particles were investigated using X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy and UV-visible-near IR spectrophotometer. XRD data confirmed the presence of single crystalline phase of Cu2O nanoparticles. FE-SEM and TEM images revealed spherical, cubic and octahedral shapes with the various particle sizes ranged from 16 to 57 nm depending on the synthesis conditions. A possible mechanism explaining the Cu2O nanostructures formation was proposed. The band gap energies of the Cu2O nanostructures were estimated and the values were located between 1.5 and 2.08 eV. Photoluminescence spectroscopy analysis clearly showed a noticeably blue-shifted emission for the synthesized samples compared to spectrum of the bulk. Eventually, magnetic properties of the synthesized nanoparticles have been measured by vibrating sample magnetometer and the attained results implied that the synthesized particles are weakly ferromagnetic in nature at normal temperature.

Excellent sun-light-driven photocatalytic activity by aurivillius layered perovskites, Bi₅-xLaxTi₃FeO₁₅ (x = 1, 2).

PubMed

Naresh, Gollapally; Mandal, Tapas Kumar

2014-12-10

Aurivillius phase layered perovskites, Bi5-xLaxTi3FeO15 (x = 1, 2) are synthesized by solid-state reaction. The compounds are characterized by powder X-ray diffraction (PXD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), UV-vis diffuse reflectance (UV-vis DRS), and photoluminescence (PL) spectroscopy. UV-vis DRS data revealed that the compounds are visible light absorbing semiconductors with band gaps ranging from ∼2.0-2.7 eV. Photocatalytic activity studies by Rhodamine B (RhB) degradation under sun-light irradiation showed that these layered oxides are very efficient photocatalysts in mild acidic medium. Scavenger test studies demonstrated that the photogenerated holes and superoxide radicals (O2(•-)) are the active species responsible for RhB degradation over the Aurivillius layered perovskites. Comparison of PL intensity, dye adsorption and ζ-potential suggested that a slow e(-)-h(+) recombination and effective dye adsorption are crucial for the degradation process over these photocatalysts. Moreover, relative positioning of the valence and conduction band edges of the semiconductors, O2/O2(•-), (•)OH/H2O potential and HOMO-LUMO levels of RhB appears to be responsible for making the degradation hole-specific. Photocatalytic cycle tests indicated high stability of the catalysts in the reaction medium without any observable loss of activity. This work shows great potential in developing novel photocatalysts with layered structures for sun-light-driven oxidation and degradation processes largely driven by holes and without any intervention of hydroxyl radicals, which is one of the most common reactive oxygen species (ROS) in many advanced oxidation processes.

Green synthesis of size controllable gold nanoparticles

NASA Astrophysics Data System (ADS)

Mohan Kumar, Kesarla; Mandal, Badal Kumar; Kiran Kumar, Hoskote A.; Maddinedi, Sireesh Babu

2013-12-01

A facile rapid green eco-friendly method to synthesize gold nanoparticles (Au NPs) of tunable size using aqueous Terminalia arjuna fruit extracts has been demonstrated herein. Formation of Au NPs was confirmed by Surface Plasmon Resonance (SPR) study at 528 nm using UV-visible spectrophotometer. The time of reduction, size and morphological variations of Au NPs were studied with varying quantities of T. arjuna fruit aqueous extracts. Synthesized Au NPs were characterized using UV-visible spectroscopy, Fourier transformed infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Energy dispersive X-ray spectroscopy (EDAX). Polyphenols responsible for reduction of Au3+ to Au0 were identified using High Performance Liquid Chromatography (HPLC) as ascorbic acid, gallic acid and pyrogallol. The oxidized forms of polyphenols formed coordination with surface of Au NPs which protected their further growth and aggregation. We also propose a plausible mechanism how to tune size and shape of Au NPs by varying the quantity of extracts. Thus obtained Au NPs were stable for more than four months.

Optical, electrochemical and thermal properties of Mn2+ doped CdS nanoparticles

NASA Astrophysics Data System (ADS)

Muruganandam, S.; Anbalagan, G.; Murugadoss, G.

2015-08-01

Mn2+ doped (1-5 and 10 %) CdS nanoparticles have been synthesized by the chemical precipitation method using polyvinylpyrrolidone as a capping agent. The particle size, morphology and optical properties have been studied by X-ray powder diffraction, transmission electron microscopy, UV-Visible and photoluminescence spectroscopy. Powder diffraction data have confirmed that the crystallite size is around 2-5 nm. The band gap of the nanoparticles has been calculated using UV-Visible absorption spectra. An optimum concentration, Mn2+ (3 %) has been selected by optical study. The functional groups of the capping agent have been identified by fourier transform infrared spectroscopy study. The presence of dopant (Mn2+) has been confirmed by electron paramagnetic resonance spectroscopy. Thermal properties of CdS:Mn2+ have been analyzed using thermogravimetric-differential thermal analyser. The electrochemical properties of the undoped and doped samples have been studied by cyclic voltammetry for electrode applications. In addition, magnetic properties of Mn2+ doped CdS have been studied using a vibrating sample magnetometer.

Fractal and spectroscopic analysis of soot from internal combustion engines

NASA Astrophysics Data System (ADS)

Swapna, M. S.; Saritha Devi, H. V.; Raj, Vimal; Sankararaman, S.

2018-03-01

Today diesel engines are used worldwide for various applications and very importantly in transportation. Hydrocarbons are the most widespread precursors among carbon sources employed in the production of carbon nanotubes (CNTs). The aging of internal combustion engine is an important parameter in deciding the carbon emission and particulate matter due to incomplete combustion of fuel. In the present work, an attempt has been made for the effective utilization of the aged engines for potential applicationapplications in fuel cells and nanoelectronics. To analyze the impact of aging, the particulate matter rich in carbon content areis collected from diesel engines of different ages. The soot with CNTs is purified by the liquid phase oxidation method and analyzed by Field Emission Scanning Electron Microscopy, High-Resolution Transmission Electron Microscopy, Energy Dispersive Spectroscopy, UV-Visible spectroscopy, Raman spectroscopy and Thermogravimetric analysis. The SEM image contains self-similar patterns probing fractal analysis. The fractal dimensions of the samples are determined by the box counting method. We could find a greater amount of single-walled carbon nanotubes (SWCNTs) in the particulate matter emitted by aged diesel engines and thereby giving information about the combustion efficiency of the engine. The SWCNT rich sample finds a wide range of applicationapplications in nanoelectronics and thereby pointing a potential use of these aged engines.

Biosynthesis of silver nanoparticles using ethanolic petals extract of Rosa indica and characterization of its antibacterial, anticancer and anti-inflammatory activities.

PubMed

Manikandan, Ramar; Manikandan, Beulaja; Raman, Thiagarajan; Arunagirinathan, Koodalingam; Prabhu, Narayanan Marimuthu; Jothi Basu, Muthuramalingam; Perumal, Muthulakshmi; Palanisamy, Subramanian; Munusamy, Arumugam

2015-03-05

The present study was aimed at biosynthesis of silver nanoparticles (AgNPs) using ethanolic extract of rose (Rosa indica) petals and testing their potential antibacterial activity using selective human pathogenic microbes, anticancer activity using human colon adenocarcinoma cancer cell line HCT 15 as well as anti-inflammatory activity using rat peritoneal macrophages in vitro. The biologically synthesized AgNPs were also characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The characterized AgNPs showed an effective antibacterial activity against Gram negative (Escherichia coli, Klebsiella pneumoniae) than Gram positive (Streptococcus mutans, Enterococcus faecalis) bacteria. MTT assay, analysis of nuclear morphology, mRNA expression of Bcl-2, Bax and protein expression of caspase 3 as well as 9, indicated potential anticancer activity. In addition, green synthesized AgNPs also attenuated cytotoxicity, nuclear morphology and free radical generation (O2(-) and NO) by rat peritoneal macrophages in vitro. The results of our study show the potential green synthesis of silver nanoparticles in mitigating their toxicity while retaining their antibacterial activities. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation and antibacterial properties of titanium-doped ZnO from different zinc salts

PubMed Central

2014-01-01

To research the relationship of micro-structures and antibacterial properties of the titanium-doped ZnO powders and probe their antibacterial mechanism, titanium-doped ZnO powders with different shapes and sizes were prepared from different zinc salts by alcohothermal method. The ZnO powders were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED), and the antibacterial activities of titanium-doped ZnO powders on Escherichia coli and Staphylococcus aureus were evaluated. Furthermore, the tested strains were characterized by SEM, and the electrical conductance variation trend of the bacterial suspension was characterized. The results indicate that the morphologies of the powders are different due to preparation from different zinc salts. The XRD results manifest that the samples synthesized from zinc acetate, zinc nitrate, and zinc chloride are zincite ZnO, and the sample synthesized from zinc sulfate is the mixture of ZnO, ZnTiO3, and ZnSO4 · 3Zn (OH)2 crystal. UV-vis spectra show that the absorption edges of the titanium-doped ZnO powders are red shifted to more than 400 nm which are prepared from zinc acetate, zinc nitrate, and zinc chloride. The antibacterial activity of titanium-doped ZnO powders synthesized from zinc chloride is optimal, and its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) are lower than 0.25 g L−1. Likewise, when the bacteria are treated by ZnO powders synthesized from zinc chloride, the bacterial cells are damaged most seriously, and the electrical conductance increment of bacterial suspension is slightly high. It can be inferred that the antibacterial properties of the titanium-doped ZnO powders are relevant to the microstructure, particle size, and the crystal. The powders can damage the cell walls; thus, the electrolyte is leaked from cells. PMID:24572014

Sonochemical Assisted Solvothermal Synthesis of Gallium Oxynitride Nanosheets and their Solar-Driven Photoelectrochemical Water-Splitting Applications.

PubMed

Iqbal, Naseer; Khan, Ibrahim; Yamani, Zain H; Qurashi, Ahsanullhaq

2016-08-26

Gallium oxynitride (GaON) nanosheets for photoelectrochemical (PEC) analysis are synthesized via direct solvothermal approach. Their FE-SEM revealed nanosheets morphology of GaON prepared at a reaction time of 24 hours at 180 °C. The elemental composition and mapping of Ga, O and N are carried out through electron dispersive X-ray spectroscopy (EDX). The cubic structure of GaON nanosheets is elucidated by X-ray diffraction (XRD)analysis. The X-ray Photoelectron Spectroscopy (XPS) further confirms Ga, O and N in their respective ratios and states. The optical properties of GaON nanosheets are evaluated via UV-Visible, Photoluminescence (PL) and Raman spectroscopy's. The band gap energy of ~1.9 eV is calculated from both absorption and diffused reflectance spectroscopy's which showed stronger p-d repulsions in the Ga (3d) and N (2p) orbitals. This effect and chemical nitridation caused upward shift of valence band and band gap reduction. The GaON nanosheets are investigated for PEC studies in a standard three electrode system under 1 Sun irradiation in 0.5 M Na2SO4. The photocurrent generation, oxidation and reduction reactions during the measurements are observed by Chronoampereometry, linear sweep Voltametry (LSV) and Cyclic Voltametry (CV) respectively. Henceforward, these GaON nanosheets can be used as potential photocatalyts for solar water splitting.

Preparation and visible light photocatalytic activity of Bi2O3/Bi2WO6 heterojunction photocatalysts

NASA Astrophysics Data System (ADS)

Yan, C. Y.; Yi, W. T.; Xiong, J.; Ma, J.

2018-03-01

The Bi2O3 nanorods, flower-like Bi2WO6 and Bi2O3/Bi2WO6 heterojunction composites with the molar ratio of nBi:nW from 2:1, 2.5:1, to 3:1 have been synthesized via one-step hydrothermal method and two-step hydrothermal method, respectively. The products are characterized by powder X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (UV-vis DRS), and scanning electron microscopy (SEM). Photocatalytic experiments indicate that such Bi2O3/Bi2WO6 composite possesses higher photocatalytic activity for RhB degradation under visible-light irradiation in comparison with pure Bi2O3 and Bi2WO6. The enhancement of the photocatalytic activity of the Bi2O3/Bi2WO6 heterojunction catalysts can be ascribed to the reduced recombination of the photoexcited electrons and holes during the photocatalytic reaction. The effect of the molar ratio of nBi:nW on the catalytic performance of the heterojunction catalysts was also investigated. And the optimal molar ratio of nBi:nW is 2.5:1 which was synthesized by one-step hydrothermal method.

Fabrication of Semi-Transparent Photovoltaic Cell by a Cost-Effective Technique

NASA Astrophysics Data System (ADS)

Nithyayini, K. N.; Ramasesha, Sheela K.

2015-09-01

Semi-transparent inorganic thin film PV cells have been fabricated using n-type (CdS) and p-type (CdTe) semiconductors. Large area devices which can be used as windows and skylights in buildings can be fabricated using cost effective solution processes. The device structure is Glass/TCO/CdTe/CdS/TCO. Chemically stable CdS and CdTe layers are deposited at temperatures 353 K to 373 K (80 °C to 100 °C) under controlled pH. The CdCl2 activation is carried out followed by air annealing. The p-n junction is formed by sintering the device at 673 K to 723 K (400 °C to 450 °C). The characterization of cells is carried out using XRD, SEM, AFM, and UV-Visible spectroscopy. The thickness of the cell is ~600 nm. The band gap values are 2.40 eV for CdS and 1.36 eV for CdTe with transmittance of about 70 pct in the visible region. Under 1.5 AM solar spectrum, V oc, and I sc of the initial device are 3.56e-01 V and 6.20e-04 A, respectively.

Synthesis and characterization of nanocomposite GO@α-Fe2O3:Efficient material for dye removal

NASA Astrophysics Data System (ADS)

Mandal, B.; Panda, J.; Tudu, B.

2018-05-01

In this work a composite of Graphene Oxide (GO) supported α-Fe2O3 nanoparticles (GF) has been synthesized via a simple co-precipitation method. Structural, and morphological study of nanocomposite (GF) are examined by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). The XRD study indicates that Graphene oxide is implanted with well crystalline α-Fe2O3 which has pure rhombohedral phase. Surface morphological study of SEM depicts sphere-like shaped α-Fe2O3 particles with formation of clusters have been embedded on Graphene oxide nano sheet. TEM image reveals that GO sheet acts as a good supporting material for anchoring nano sized α -Fe2O3 particles. Efficiency of dye removal of the prepared GF composite has been measured by the degradation of methylene blue (MB) in an aqueous solution under visible light irradiation. The degradation of the dye has been evaluated by a UV-visible spectroscopy, by decrease in the intensity of absorbance and concentration. The degradation efficiency of GF is found to be 90% towards MB.

In situ synthesis of CdS/CdWO4/WO3 heterojunction films with enhanced photoelectrochemical properties

NASA Astrophysics Data System (ADS)

Zhan, Faqi; Li, Jie; Li, Wenzhang; Yang, Yahui; Liu, Wenhua; Li, Yaomin

2016-09-01

CdS/CdWO4/WO3 heterojunction films on fluorine-doped tin oxide (FTO) substrates are for the first time prepared as an efficient photoanode for photoelectrochemical (PEC) hydrogen generation by an in situ conversion process. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet visible spectrometry (UV-vis) and X-ray photoelectron spectroscopy (XPS). The CdS hollow spheres (∼80 nm) sensitized WO3 plate film with a CdWO4 buffer-layer exhibits increased visible light absorption and a significantly improved photoelectrochemical performance. The photocurrent density at 0 V (vs. Ag/AgCl) of the CdS/CdWO4/WO3 anode is ∼3 times higher than that of the CdWO4/WO3 anode, and ∼9 times higher than that of pure WO3 under illumination. The highest incident-photon-to-current-efficiency (IPCE) value increased from 16% to 63% when the ternary heterojunction was formed. This study demonstrates that the synthesis of ternary composite photocatalysts by the in situ conversion process may be a promising approach to achieve high photoelectric conversion efficiency.

FTIR Study of the Photoactivation Process of Xenopus (6-4) Photolyase†

PubMed Central

Yamada, Daichi; Zhang, Yu; Iwata, Tatsuya; Hitomi, Kenichi; Getzoff, Elizabeth D.; Kandori, Hideki

2012-01-01

Photolyases (PHRs) are blue-light activated DNA repair enzymes that maintain genetic integrity by reverting UV-induced photoproducts into normal bases. The FAD chromophore of PHRs has four different redox states: oxidized (FADox), anion radical (FAD•−), neutral radical (FADH•) and fully reduced (FADH−). We combined difference Fourier-transform infrared (FTIR) spectroscopy with UV-visible spectroscopy to study the detailed photoactivation process of Xenopus (6-4) PHR. Two photons produce the enzymatically active, fully reduced PHR from oxidized FAD: FADox is converted to semiquinone via light-induced one-electron and one-proton transfers, and then to FADH− by light-induced one-electron transfer. We successfully trapped FAD•− at 200 K, where electron transfer occurs, but proton transfer does not. UV-visible spectroscopy following 450-nm illumination of FADox at 277 K defined the FADH•/FADH− mixture and allowed calculation of difference FTIR spectra among the four redox states. The absence of a characteristic C=O stretching vibration indicated that the proton donor is not a protonated carboxylic acid. Structural changes in Trp and Tyr are suggested from UV-visible and FTIR analysis of FAD•− at 200 K. Spectral analysis of amide-I vibrations revealed structural perturbation of the protein’s β-sheet during initial electron transfer (FAD•− formation), transient increase in α-helicity during proton transfer (FADH• formation) and reversion to the initial amide-I signal following subsequent electron transfer (FADH− formation). Consequently, in (6-4) PHR, unlike cryptochrome-DASH, formation of enzymatically active FADH− did not perturb α-helicity. Protein structural changes in the photoactivation of (6-4) PHR are discussed on the basis of the present FTIR observations. PMID:22747528

Green synthesis of silver nanoparticles using Alternanthera dentata leaf extract at room temperature and their antimicrobial activity

NASA Astrophysics Data System (ADS)

Kumar, Deenadayalan Ashok; Palanichamy, V.; Roopan, Selvaraj Mohana

2014-06-01

A green rapid biogenic synthesis of silver nanoparticles AgNPs using Alternanthera dentata (A. dentata) aqueous extract was demonstrated in this present study. The formation of silver nanoparticles was confirmed by Surface Plasmon Resonance (SPR) at 430 nm using UV-visible spectrophotometer. The reduction of silver ions to silver nanoparticles by A. dentata extract was completed within 10 min. Synthesized nanoparticles were characterized using UV-visible spectroscopy; Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM). The extracellular silver nanoparticles synthesis by aqueous leaf extract demonstrates rapid, simple and inexpensive method comparable to chemical and microbial methods. The colloidal solution of silver nanoparticles were found to exhibit antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia and, Enterococcus faecalis.

Studies of surface morphology and optical properties of ZnO nanostructures grown on different molarities of TiO{sub 2} seed layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asib, N. A. M., E-mail: amierahasib@yahoo.com; Afaah, A. N.; Aadila, A.

Titanium dioxide (TiO{sub 2}) seed layer was prepared by using sol-gel spin-coating technique, followed by growth of 0.01 M of Zinc oxide (ZnO) nanostructures by solution-immersion. The molarities of TiO{sub 2} seed layer were varied from 1.1 M to 0.100 M on glass substrates. The nanostructures thin films were characterized by Field Emission Scanning Electrons Microscope (FESEM), Photoluminescence (PL) spectroscopy and Ultraviolet-Visible (UV-Vis) spectroscopy. FESEM images demonstrate that needle-like ZnO nanostructures are formed on all TiO{sub 2} seed layer. The smallest diameter of needle-like ZnO nanostructures (90.3 nm) were deposited on TiO{sub 2} seed layer of 0.100 M. PL spectramore » of the TiO{sub 2}: ZnO nanostructures thin films show the blue shifted emissions in the UV regions compared to the ZnO thin film. Meanwhile, UV-vis spectra of films display high absorption in the UV region and high trasparency in the visible region. The highest absorbance at UV region was recorded for sample which has 0.100 M of TiO{sub 2} seed layer.« less

Photodecolorisation of melanoidins in vinasse with illuminated TiO2-ZnO/activated carbon composite.

PubMed

Otieno, Benton O; Apollo, Seth O; Naidoo, Bobby E; Ochieng, Aoyi

2017-06-07

A hybrid photo-catalyst, TiO 2 -ZnO, was synthesized by immobilizing ZnO on commercial TiO 2 (aeroxide P25). Activated carbon (AC) was subsequently used to support the hybrid, thus forming a TiO 2 -ZnO/AC composite catalyst. Fourier transform infrared (FTIR) analysis and scanning electron microscopy integrated with energy-dispersive X-ray spectroscopy (SEM-EDX) investigations revealed successful catalyst synthesis. Optical properties of the hybrid determined from photoluminescence (PL) and Ultraviolet-visible (UV-vis) spectroscopy confirmed a restrained recombination of electron-hole pairs and reduced energy band gap due to a successful heterojunction formation. The prepared catalysts were used to photodecolorise vinasse in a 12-W UVC batch photoreactor. TiO 2 -ZnO had improved photocatalytic activity compared with TiO 2 and ZnO separately. On supporting the hybrid onto AC, both adsorption and photocatalytic activities were further enhanced with improved overall color removal of 86% from 68%. Photodecolorisation followed the pseudo-first-order reaction model with the rate constant ([Formula: see text]) observed decreasing from 0.0701 to 0.0436 min -1 on increasing the initial concentration from 5,000 to 14,000 ppm. The UV process was found to be 33-fold less energy intensive for color reduction as compared to total organic carbon (TOC) reduction. Formation of nitrates during the photodecolorisation process was attributed to the mineralization of nitrogen heteroatoms in the color-causing melanoidin compounds.

Investigating the Synthesis and Characterization of a Novel "Green" H₂O₂-Assisted, Water-Soluble Chitosan/Polyvinyl Alcohol Nanofiber for Environmental End Uses.

PubMed

Pervez, Md Nahid; Stylios, George K

2018-06-01

The present work highlights the formation of a novel green nanofiber based on H₂O₂-assisted water-soluble chitosan/polyvinyl alcohol (W S CHT/PVA) by using water as an ecofriendly solvent and genipin used as a nontoxic cross-linker. The 20/80 blend ratio was found to have the most optimum uniform fiber morphology. W S CHT retained the same structure as W IS CHT. The prepared nanofibers were characterized by Scanning electron microscopy (SEM), Fourier transform spectroscopy (FTIR), Thermo gravimetric analysis (TGA), Differential scanning calorimeter (DSC), X-ray diffraction (XRD), Water Contact Angle (WCA) and Ultraviolet-visible spectroscopy (UV-vis). During electrospinning, the crystalline microstructure of the W S CHT/PVA underwent better solidification and after cross-linking there was an increase in the melting temperature of the fiber. Swelling ratio studies revealed noticeable increase in hydrophilicity with increase of W S CHT, which was further demonstrated by the decrease of contact angle from 64.74° to 14.68°. W S CHT/PVA nanofiber mats exhibit excellent UV blocking protection with less than 5% transmittance value and also showed improved in vitro drug release properties with stable release for longer duration (cross-linked fibers) and burst release for shorter duration (uncross linked) fibers. Finally our experimental data demonstrates excellent adsorption ability of Colour Index (C.I.) reactive black 5 (RB5) due to protonated amino groups.

Fabrication of solar light induced Fe-TiO{sub 2} immobilized on glass-fiber and application for phenol photocatalytic degradation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Shaohua, E-mail: linsh75@163.com; Zhang, Xiwang; Sun, Qinju

2013-11-15

Graphical abstract: - Highlights: • Fe-doped TiO{sub 2} immobilized on glass-fiber net were prepared by sol–gel method. • Fe inhibited the phase transition of TiO{sub 2} from anatase to rutile. • The optimal Fe doping dose was around 0.005 wt%. • The optimal calcination temperature was around 600 °C. - Abstract: Iron-doped anatase titanium dioxide catalysts coated on glass-fiber were successfully synthesized by a dip-coating sol–gel method. The prepared catalysts were characterized by scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy to understand the synthesis mechanism, and their photocatalytic activities weremore » evaluated by photodegradation of phenol under simulated solar irradiation. EDX analysis confirmed the existence of iron in the immobilized catalysts. XRD suggested that the phase transition of the catalysts from anatase to rutile were restrained, and almost pure anatase TiO{sub 2} could retain even the calcination temperature reached 800 °C. The UV-Vis diffuse reflectance spectroscopy of the catalysts showed a red shift and increased photoabsorbance in the visible range for all the doped samples. Iron loading and calcination temperature have obvious influences on photocatalytic activity. In this study, the optimal doping dose and calcination temperature were around 0.005 wt% and 600 °C, respectively.« less

Colloidal silver nanoparticles prepared by UV-light induced citrate reduction technique for the quantitative detection of uric acid

NASA Astrophysics Data System (ADS)

Maity, Anupam; Panda, Sovan Kumar

2018-04-01

Reddish-yellow color colloid consisting of silver nanoparticles (Ag NPs) has been synthesized by reducing aqueous AgNO3 solution by photo-induced citrate reduction technique under UV light. As prepared colloid exhibits single and intense plasmonic absorption peak in the violet region of the visible spectra with the peak centered at 405 nm. The NPs are fine and spherical with diameter ranging from 5 to 10 nm. These colloidal NPs have been used for the quantitative detection of uric acid by UV-VIS spectroscopy. A linear red shifting of the characteristics Plasmonic absorption peak of Ag NPs is observed with uric acid concentration. Uric acid can be detected by UV-VIS spectroscopy down to 5 nM limit using the prepared colloid.

Elaboration, structural and optical investigations of ZnO/epoxy nanocomposites

NASA Astrophysics Data System (ADS)

Moussa, S.; Namouchi, F.; Guermazi, H.

2015-07-01

Hybrid nanocomposites were elaborated by incorporating ZnO nanoparticles into a transparent epoxy polymer matrix, using the direct dispersion method. The effect of the nanoparticles on the structural and optical properties of the polymer matrix was investigated using Fourier transform infrared (FTIR), Raman and UV-Visible spectroscopies. Nanocomposites FTIR spectra showed a variation of band intensities attributed to nanoparticles agglomeration within the polymer. The UV-Visible measurements showed a redshift on the band gap energy of the nanocomposites differently from neat epoxy resin, caused by interactions between ZnO NPs and polymer chains. Raman spectra confirm these interactions and the formation of hydrogen bonds in the nanocomposites. The UV-Visible transmittance spectra revealed that addition of a very low concentration (0.2wt%) of ZnO nanoparticles to a transparent epoxy matrix would maintain high visible-light transparency. The decrease of transmittance with increasing ZnO percentage is due to light scattering which originates from the agglomeration of nanoparticles in the matrix, the mismatch between the refractive index of ZnO and that of the epoxy matrix, and the increase of the surface roughness of the nanocomposite with increasing ZnO addition. Moreover, the UV-vis absorption spectra revealed that adding more than 1wt% ZnO leads to the improvement of the UV shielding properties of the nanocomposites. These results prove that the elaborated ZnO/epoxy nanocomposites can be used as UV shielding materials.

Designing MgFe2O4 decorated on green mediated reduced graphene oxide sheets showing photocatalytic performance and luminescence property

NASA Astrophysics Data System (ADS)

Shetty, Krushitha; Lokesh, S. V.; Rangappa, Dinesh; Nagaswarupa, H. P.; Nagabhushana, H.; Anantharaju, K. S.; Prashantha, S. C.; Vidya, Y. S.; Sharma, S. C.

2017-02-01

Here, a green route has been reported to convert Graphene Oxide (GO) to reduced graphene oxide (RGO) using clove extract. A modest and eco-accommodating sol-gel strategy has been employed to prepare MgFe2O4 nanoparticles, MgFe2O4-RGO nanocomposite samples. The samples were analyzed by Powder X-ray diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR), UV-Visible Spectroscopy, Scanning Electron Microcopy (SEM), Transmission Electron Microscopy (TEM), Photoluminescence (PL) and Electrochemical Impedance Spectroscopy (EIS). PXRD result revealed that the prepared samples were cubic spinel in nature. SEM results uncovered flake like surface morphology of the prepared nanomaterial. Better PL emission signature was observed when excited at 329 nm. PL studies demonstrated that the present samples were potential for the fabrication of white component of white light emitting diodes (WLEDs). Further, MgFe2O4-RGO nanocomposite showed enhanced photocatalytic movement (PCM) and photostability under Sunlight in the decomposition of Malachite Green (MG) compared to MgFe2O4. This can be attributed to the interaction of MgFe2O4 surface with RGO sheets which results in PL quenching, demonstrates that the recombination of photo-induced electrons and holes in MgFe2O4-RGO nanocomposite is more effectively inhibited. A possible mechanism for the enhanced properties of MgFe2O4-RGO nanocomposite was discussed. Moreover, MgFe2O4-RGO photocatalyst also showed easy magnetic separation with high reusability. These results unveil that the synthesized sample can be used in display applications and also as a potential photocatalyst.

Control of the shape and size of iron oxide (α-Fe2O3) nanoparticles synthesized through the chemical precipitation method

NASA Astrophysics Data System (ADS)

Lassoued, Abdelmajid; Dkhil, Brahim; Gadri, Abdellatif; Ammar, Salah

Hematite (α-Fe2O3) nanoparticles were synthesized via a simple chemical precipitation method. The impact of varying the concentration of precursor on the crystalline phase, size and morphology of α-Fe2O3 products was explored. The characteristic of the synthesized hematite nanoparticles were evaluated by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR) spectroscopy, Raman spectroscopy, Differential Thermal Analysis (DTA), Thermo Gravimetric Analysis (TGA), Ultraviolet-Visible (UV-Vis) analysis and Photoluminescence (PL). XRD data revealed a rhombohedral (hexagonal) structure with the space group R-3c in all samples. Uniform spherical like morphology was confirmed by TEM and SEM. The result revealed that the particle sizes were varied between 21 and 82 nm and that the increase in precursor concentration (FeCl3, 6H2O) is accompanied by an increase in the particle size of 21 nm for pure α-Fe2O3 synthesized with [Fe3+] = 0.05 M at 82 nm for pure α-Fe2O3 synthesized with [Fe3+] = 0.4 M. FT-IR confirms the phase purity of the nanoparticles synthesized. The Raman spectroscopy was used not only to prove that we have synthesized pure hematite but also to identify their phonon modes. The thermal behavior of compound was studied by using TGA/DTA results: The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. Besides, the optical investigation revealed that samples have an optical gap of about 2.1 eV and that this value varies as a function of the precursor concentration.

Synthesis and anion recognition studies of novel bis (4-hydroxycoumarin) methane azo dyes

NASA Astrophysics Data System (ADS)

Panitsiri, Amorn; Tongkhan, Sukanya; Radchatawedchakoon, Widchaya; Sakee, Uthai

2016-03-01

Four new bis (4-hydroxycoumarin) methane azo dyes were synthesized by the condensation of 4-hydroxycoumarin with four different azo salicylaldehydes and their structures were characterized by FT-IR, 1H NMR, 13C NMR, HRMS. Anion binding ability in dimethyl sulfoxide (DMSO) solutions with tetrabutylammonium (TBA) salts (F-, Cl-, Br-, I-, AcO- and H2PO4-) was investigated by the naked eye, as well as UV-visible spectroscopy. The sensor shows selective recognition towards fluoride and acetate. The binding affinity of the sensors with fluoride and acetate was calculated using UV-visible spectroscopic technique.

Visible light photo catalytic inactivation of bacteria and photo degradation of methylene blue with Ag/TiO2 nanocomposite prepared by a novel method.

PubMed

Tahir, Kamran; Ahmad, Aftab; Li, Baoshan; Nazir, Sadia; Khan, Arif Ullah; Nasir, Tabassum; Khan, Zia Ul Haq; Naz, Rubina; Raza, Muslim

2016-09-01

Water purification is one of the worldwide problem and most of the conventional methods are associated with a number of drawbacks. Therefore it is the need of the day to develop new methods and materials to overcome the problem of water purification. In this research work we present a simple and green approach to synthesize silver decorated titanium dioxide (Ag/TiO2) nanocomposite with an efficient photo catalytic activities. Phytochemicals of the Cestrum nocturnum leaf extract were used to synthesize silver nanoparticles (AgNPs), Titanium dioxide (TiO2) and Ag/TiO2 nanocomposite. To confirm the formation, crystal structure, particle size and shape of green synthesized nanoparticles and nanocomposite, they were characterized by UV-visible spectroscopy (UV-vis), X-ray diffraction spectroscopy (XRD), high resolution transmission electron microscopy (HRTEM), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The AgNPs, TiO2 and Ag/TiO2 were evaluated for photo degradation of methylene blue (MB) and photo inhibition of Bacteria. The bio-synthesized Ag/TiO2 nanocomposite was observed to have strong catalytic activities for photo reduction of MB and photo inactivation of bacteria as compared to bare AgNPs and TiO2. In the presence of Ag/TiO2, 90% of MB was degraded only in 40min of irradiation. Alternatively the bare AgNPs and TiO2 degraded less than 30% and 80% respectively of MB even in more than 100min of irradiation. Similarly the Ag/TiO2 has very strong photo inhibition efficiency towards Escherichia coli and Pseudomonas aeruginosa. The zone of inhibition of irradiated Ag/TiO2 nanocomposites against E. coli and P. aeruginosa was 19mm and 17mm respectively which was two times higher than in dark. These promising photocatalytic activities of nanocomposite may be due to the highly decorated AgNPs over the surface of TiO2. Copyright © 2016 Elsevier B.V. All rights reserved.

Improving the Photocatalytic Activity of Modified Anatase TiO2 with Different Concentrations of Aluminum under Visible Light: Mechanistic Survey.

PubMed

Afshar, Shahrara; Pordel, Shabnam; Tahmouresilerd, Babak; Azad, Alireza

2016-11-01

Visible light-driven Al-doped TiO 2 with different aluminum contents (2, 5 and 10 mol%) were synthesized via a facile sol-gel method. Fourier transform infrared (FTIR), UV-visible diffuse reflectance, energy dispersive X-ray (EDX) spectroscopy as well as X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron microscopy (SEM) methods were used for the characterization of the obtained nanoparticles. The photocatalytic performance of the samples was evaluated by the degradation of rhodamine B (RhB) under visible light irradiation. The yield of the degradation RhB was estimated to be 71%, 89%, 65% and 56%, for the bare TiO 2 , 2%, 5% and 10% Al-doped TiO 2 , respectively. It was found that 2 mol% of Al-doped TiO 2 shows the best photocatalytic performance. In low concentration of dopant, separation of photogenerated electron-hole pairs promoted, and subsequently, the degradation efficiency increased. It was proposed that the degradation of RhB by 2 mol% Al-doped TiO 2 photocatalyst follows both N-deethylation and chromophore cleavage mechanisms, while the N-deethylation still predominated over cleavage of dye chromophore structure. The key role of hydroxyl radicals in RhB degradation was verified by the effects of scavengers. In addition, the photocatalyst can be reused for three runs without any significant loss of its catalytic activity. © 2016 The American Society of Photobiology.

Interaction of flavonoids, the naturally occurring antioxidants with different media: a UV-visible spectroscopic study.

PubMed

Naseem, Bushra; Shah, S W H; Hasan, Aurangzeb; Sakhawat Shah, S

2010-04-01

Quantitative parameters for interaction of flavonoids-the naturally occurring antioxidants, with solvents and surfactants are determined using UV-visible absorption spectroscopy. The availability of flavonoids; kaempferol, apigenin, kaempferide and rhamnetin in micelles of sodium dodecyl sulfate (SDS) is reflected in terms of partition coefficient, K(c). Thermodynamic calculations show that the process of transfer of flavonoid molecules to anionic micelles of SDS is energy efficient. A distortion in flavonoid's morphology occurs in case of kaempferol and apigenin in surfactant and water, exhibited in terms of a new band in the UV region of electronic spectra of these flavonoids. The partition coefficients of structurally related flavonoids are correlated with their antioxidant activities. Copyright 2010 Elsevier B.V. All rights reserved.

Structure of the Global Nanoscience and Nanotechnology Research Literature

DTIC Science & Technology

2006-01-01

Transistors, Nature, 424 (6949): 654-657, 2003. Joannopoulos, JD, Meade, RD, Winn, JN, Photonic Crystals: Molding the Flow of Light, Princeton...1.27 Force Microscopy 40 0.10 0.00 Electron Spectroscopy 40 0.10 0.00 Rutherford backscattering spectrometry 38 0.10 0.00 flow cytometry 36 0.09...Backscattering Spectroscopy/Spectrometry • Flow Cytometry • Spectrophotometry (UV-Visible) • Deep Level Transient Spectroscopy • Inductively

A low-cost visible light activeBiFeWO6/TiO2nanocompositewith an efficient photocatalytic and photoelectrochemical performance

NASA Astrophysics Data System (ADS)

Priya, A.; Arunachalam, Prabhakarn; Selvi, A.; Madhavan, J.; Al-Mayouf, Abdullah M.; Ghanem, Mohamed A.

2018-07-01

Herein, visible-light driven BiFeWO6/TiO2 nanocomposites photocatalysts were successfully synthesized by an incipient wet-impregnation method. The as-synthesized BiFeWO6/TiO2 nanocomposites were explored by using various techniques of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, UV-vis diffuse reflection spectroscopy (DRS), photoluminescence (PL), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoelectrochemical (PEC) studies to investigate the material formation, surface morphology, electrochemical and optical behaviors. Furthermore, the photocatalytic efficiency of fabricated BiFeWO6/TiO2 nanocomposites was also evaluated towards the degradation of acid orange 7 (AO7). From the degradation results, it revealed that 1% BiFeWO6/TiO2 nanocomposite demonstrated superior photocatalytic performance than its comparison with pure components. This optimized 1% BiFeWO6/TiO2 nanocomposite was found to achieve complete degradation of AO7 within 60 min and also it showing a rate constant value of0.054 min-1 which is much superior to the pure TiO2. This improvement might be credited to its strong light absorption ability in a visible-light region and the low recombination rate of hole-electron pairs. Also, the BiFeWO6/TiO2 nanocomposite has an exceptional photostability and reusability character along with an excellent photo-electrochemical activity. Therefore, it can be well useful material for removing organic pollutants in the aqueous environment. Finally, a probable mechanism is suggested for the photodegradation of AO7 over as-synthesized BiFeWO6/TiO2nanocomposite material.

AgCl/Ag3PO4: A stable Ag-Based nanocomposite photocatalyst with enhanced photocatalytic activity for the degradation of parabens.

PubMed

Guo, Jianhao; Shi, Huixian; Huang, Xiaobo; Shi, Huifang; An, Zhongfu

2018-04-01

An AgCl/Ag 3 PO 4 composite has been successfully fabricated by a simple desorption-precipitation method. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV/Vis), and photoluminescence (PL) have been used to study the structural and physicochemical characteristics of the AgCl/Ag 3 PO 4 composite. The photocatalytic activity of the AgCl/Ag 3 PO 4 composite has been tested by the degradation of parabens under visible-light irradiation. 100% of MPB was degraded within 40 min in the AgCl/Ag 3 PO 4 -visible light system. Moreover, the photocatalytic activity of AgCl/Ag 3 PO 4 remained at 94% of the original level after five runs, which was much higher than that of pure Ag 3 PO 4 (25%). The obtained results confirmed that the AgCl/Ag 3 PO 4 composite exhibited significantly higher photocatalytic performance and improved stability compared with bare Ag 3 PO 4 . The enhanced photocatalytic performance of the AgCl/Ag 3 PO 4 composite could be mainly attributed to highly efficient charge separation through a synergistic effect of AgCl, Ag 3 PO 4 , and in situ photo-reduced Ag nanoparticles. Trapping experiments confirmed h + and ·O 2 - to be the two main active species in the photocatalytic process. Finally, a possible photocatalytic mechanism for the charge-transfer process is proposed to account for the enhanced photocatalytic performance of the AgCl/Ag 3 PO 4 composite. Copyright © 2018 Elsevier Inc. All rights reserved.

The Photocatalytic Application of Semiconductor Stibnite Nanostructure Synthesized via a Simple Microwave-Assisted Approach in Propylene Glycol for Degradation of Dye Pollutants and its Optical Property

NASA Astrophysics Data System (ADS)

Saksornchai, Eksuree; Kavinchan, Jutarat; Thongtem, Somchai; Thongtem, Titipun

2017-11-01

Stibnite (Sb2S3) semiconducting material was successfully synthesized by a rapid and facile microwave route using antimony chloride (SbCl3) and sodiumthiosulfate (Na2S2O3) dissolved in propylene glycol (PG) containing different hydroxyethyl cellulose (HEC) masses. The phase identification, morphology, and elemental composition of products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field- emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The results revealed the orthorhombic phase of Sb2S3 single crystal-forming sheaf-like nanostructure, and a possible formation mechanism was proposed and discussed. Its direct band gap calculated from UV-visible absorption is 1.60 eV. In this research, the photocatalytic activities of Sb2S3 nanostructure were investigated through the degradation of methyl orange (MO) and methylene blue (MB) under visible light irradiation. The as-obtained 0.30 g HEC-added solution (0.3 HEC-Sb2S3) photocatalyst exhibited better photocatalytic activity than the other products, which degraded 91% of MO within 300 min and 90% of MB within 240 min under the Xe-lamp irradiation. The first-order plot was fitted with this experiment which the rate constant ( k) of 0.3 HEC-Sb2S3 for MO and MB degradation are 0.0085 and 0.0098 min-1, respectively. Therefore, the new experience with a novel and simple synthetic procedure of Sb2S3 photocatalyst that exhibits the characteristics of a highly effective photocatalyst under visible light irradiation was discovered.

Quantification of Coffea arabica and Coffea canephora var. robusta concentration in blends by means of synchronous fluorescence and UV-Vis spectroscopies.

PubMed

Dankowska, A; Domagała, A; Kowalewski, W

2017-09-01

The potential of fluorescence, UV-Vis spectroscopies as well as the low- and mid-level data fusion of both spectroscopies for the quantification of concentrations of roasted Coffea arabica and Coffea canephora var. robusta in coffee blends was investigated. Principal component analysis was used to reduce data multidimensionality. To calculate the level of undeclared addition, multiple linear regression (PCA-MLR) models were used with lowest root mean square error of calibration (RMSEC) of 3.6% and root mean square error of cross-validation (RMSECV) of 7.9%. LDA analysis was applied to fluorescence intensities and UV spectra of Coffea arabica, canephora samples, and their mixtures in order to examine classification ability. The best performance of PCA-LDA analysis was observed for data fusion of UV and fluorescence intensity measurements at wavelength interval of 60nm. LDA showed that data fusion can achieve over 96% of correct classifications (sensitivity) in the test set and 100% of correct classifications in the training set, with low-level data fusion. The corresponding results for individual spectroscopies ranged from 90% (UV-Vis spectroscopy) to 77% (synchronous fluorescence) in the test set, and from 93% to 97% in the training set. The results demonstrate that fluorescence, UV, and visible spectroscopies complement each other, giving a complementary effect for the quantification of roasted Coffea arabica and Coffea canephora var. robusta concentration in blends. Copyright © 2017 Elsevier B.V. All rights reserved.

Photocatalytic degradation of Rhodamine B dye using Fe doped TiO2 nanocomposites

NASA Astrophysics Data System (ADS)

Barkhade, Tejal; Banerjee, Indrani

2018-05-01

The unique properties of titanium dioxide (TiO2) such as high photo catalytic activity, high chemical stability and low toxicity have made it a suitable photocatalyst in recent decades. The effect of modification of TiO2 with doping of iron on its characteristics and photo catalytic efficiency was studied. The change in band gap energy of TiO2 nanoparticles after doping with Fe has been studied. Significant enhancement in photo catalytic property of TiO2 after Fe doping under light exposure conditions has been investigated. Acute exposure to non-biodegradable Rhodamine B resulted in many health problems like burning of eyes, skin irritation, nasal burning, and chest pain etc. Therefore, degradation of this dye is needed to save environment and animals. Considering the similar radius of Fe3+ and Ti4+ ions (respectively 0.64 Å and 0.68 Å), titanium position in the lattice of TiO2 can be replaced by iron cations easily. The undoped and Fe doped TiO2 nano composites were synthesized by sol-gel method, in which 1.0M% of Fe was doped with TiO2 and then the samples were characterized by using FE-SEM, UV-Visible diffuse spectroscopy, Raman Spectroscopy, and FTIR. Photo catalytic degradation of Rhodamine B dye experiment was carried out in visible light range. After 90 min time duration pink colour of dye turned colourless, indicating significant degradation rate with time.

Traceability of Boletaceae mushrooms using data fusion of UV-visible and FTIR combined with chemometrics methods.

PubMed

Yao, Sen; Li, Tao; Liu, HongGao; Li, JieQing; Wang, YuanZhong

2018-04-01

Boletaceae mushrooms are wild-grown edible mushrooms that have high nutrition, delicious flavor and large economic value distributing in Yunnan Province, China. Traceability is important for the authentication and quality assessment of Boletaceae mushrooms. In this study, UV-visible and Fourier transform infrared (FTIR) spectroscopies were applied for traceability of 247 Boletaceae mushroom samples in combination with chemometrics. Compared with a single spectroscopy technique, data fusion strategy can obviously improve the classification performance in partial least square discriminant analysis (PLS-DA) and grid-search support vector machine (GS-SVM) models, for both species and geographical origin traceability. In addition, PLS-DA and GS-SVM models can provide 100.00% accuracy for species traceability and have reliable evaluation parameters. For geographical origin traceability, the accuracy of prediction in the PLS-DA model by data fusion was just 64.63%, but the GS-SVM model based on data fusion was 100.00%. The results demonstrated that the data fusion strategy of UV-visible and FTIR combined with GS-SVM could provide a higher synergic effect for traceability of Boletaceae mushrooms and have a good generalization ability for the comprehensive quality control and evaluation of similar foods. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Synthesis and structural characterization of magnetic cadmium sulfide-cobalt ferrite nanocomposite, and study of its activity for dyes degradation under ultrasound

NASA Astrophysics Data System (ADS)

Farhadi, Saeed; Siadatnasab, Firouzeh

2016-11-01

Cadmium sulfide-cobalt ferrite (CdS/CFO) nanocomposite was easily synthesized by one-step hydrothermal decomposition of cadmium diethyldithiocarbamate complex on the CoFe2O4 nanoparticles at 200 °C. Spectroscopic techniques of powder X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-visible spectroscopy, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), and magnetic measurements were applied for characterizing the structure and morphology of the product. The results of FT-IR, XRD and EDX indicated that the CdS/CFO was highly pure. SEM and TEM results revealed that the CdS/CFO nanocomposite was formed from nearly uniform and sphere-like nanoparticles with the size of approximately 20 nm. The UV-vis absorption spectrum of the CdS/CFO nanocomposite showed the band gap of 2.21 eV, which made it suitable for sono-/photo catalytic purposes. By using the obtained CdS/CFO nanocomposite, an ultrasound-assisted advanced oxidation process (AOP) has been developed for catalytic degradation of methylene blue (MB), Rhodamine B (RhB), and methyl orange (MO)) in the presence of H2O2 as a green oxidant. CdS/CFO nanocomposite exhibited excellent sonocatalytic activity, so that, dyes were completely degraded in less than 10 min. The influences of crucial factors such as the H2O2 amount and catalyst dosage on the degradation efficiency were evaluated. The as-prepared CdS/CFO nanocomposite exhibited higher catalytic activity than pure CdS nanoparticles. Moreover, the magnetic property of CoFe2O4 made the nanocomposite recyclable.

Control of average spacing of OMCVD grown gold nanoparticles

NASA Astrophysics Data System (ADS)

Rezaee, Asad

Metallic nanostructures and their applications is a rapidly expanding field. Nobel metals such as silver and gold have historically been used to demonstrate plasmon effects due to their strong resonances, which occur in the visible part of the electromagnetic spectrum. Localized surface plasmon resonance (LSPR) produces an enhanced electromagnetic field at the interface between a gold nanoparticle (Au NP) and the surrounding dielectric. This enhanced field can be used for metal-dielectric interfacesensitive optical interactions that form a powerful basis for optical sensing. In addition to the surrounding material, the LSPR spectral position and width depend on the size, shape, and average spacing between these particles. Au NP LSPR based sensors depict their highest sensitivity with optimized parameters and usually operate by investigating absorption peak: shifts. The absorption peak: of randomly deposited Au NPs on surfaces is mostly broad. As a result, the absorption peak: shifts, upon binding of a material onto Au NPs might not be very clear for further analysis. Therefore, novel methods based on three well-known techniques, self-assembly, ion irradiation, and organo-meta1lic chemical vapour deposition (OMCVD) are introduced to control the average-spacing between Au NPs. In addition to covalently binding and other advantages of OMCVD grown Au NPs, interesting optical features due to their non-spherical shapes are presented. The first step towards the average-spacing control is to uniformly form self-assembled monolayers (SAMs) of octadecyltrichlorosilane (OTS) as resists for OMCVD Au NPs. The formation and optimization of the OTS SAMs are extensively studied. The optimized resist SAMs are ion-irradiated by a focused ion beam (Fill) and ions generated by a Tandem accelerator. The irradiated areas are refilled with 3-mercaptopropyl-trimethoxysilane (MPTS) to provide nucleation sites for the OMCVD Au NP growth. Each step during sample preparation is monitored by using surface characterization methods such as contact angle measurements, ellipsometry, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), Rutherford backscattering spectroscopy (RBS), UV-Visible spectroscopy, and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). Keywords: Absorption, Array, Average Spacing, Binary Mixture, Density, Deposition, Dose, Fm, Gold Nanoparticle, Growth, Ion Irradiation, LSPR, Nanolithography, Nearest Neighbour Distance, OMCVD, Optical Response, OTS, Polarization, Refilling, Resist, SAM, Self-assembly, SEM Image Analysis, Sensing, Surface, Thin Film, Transparent Substrate.

Enhanced visible-light-driven photocatalytic bacteria disinfection by g-C3N4-AgBr.

PubMed

Deng, Jun; Liang, Jialiang; Li, Mian; Tong, Meiping

2017-04-01

g-C 3 N 4 -AgBr was synthesized by depositing AgBr nanoparticles onto g-C 3 N 4 . Scanning electron microscopy (SEM), Transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS) and Photoluminescence (PL) spectra were employed to characterize the as-synthesized photocatalysts. The disinfection activities towards representative Gram-negative strain E. coli and Gram-positive strain S. aureus were examined under visible light irradiation. Complete inactivation of 3×10 6 CFU/mL viable cell density was reached in 60min for E. coli and 150min for S. aureus, respectively. Ag + released from the photocatalysts did not contribute to the photocatalytic disinfection process. Direct contact of g-C 3 N 4 -AgBr composites and bacterial cells, as well as the presence of O 2 was indispensable for the cell inactivation. Photo-generated holes, surface bounded OH, and indirect generation of intracellular active species played important roles in disinfection process of g-C 3 N 4 -AgBr under visible light irradiation. The disruption of outside structure of cells as well as inner cell injury led to the inactivation. High pH condition led to increasing the cell disinfection due to the generation of surface bounded OH. Copyright © 2017 Elsevier B.V. All rights reserved.

Photoelectrocatalytic degradation of atrazine by boron-fluorine co-doped TiO2 nanotube arrays.

PubMed

Wang, He-Xuan; Zhu, Li-Nan; Guo, Fu-Qiao

2018-06-23

Atrazine, one of the most widespread herbicides in the world, is considered as an environmental estrogen and has potential carcinogenicity. In this study, atrazine was degraded on boron-fluorine co-doped TiO 2 nanotube arrays (B, F-TiO 2 NTAs), which had similar morphology with the pristine TiO 2 NTAs. The structure and morphology of TiO 2 nanotube samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-visible diffuse reflectance spectroscopy (DRS). It showed that the decoration of fluorine and boron made both the absorption in the visible region enhanced and the band edge absorption shifted. The efficiency of atrazine degradation by B, F-TiO 2 NTAs through photoelectrocatalysis was investigated by current, solution pH, and electrolyte concentration, respectively. The atrazine removal rate reached 76% through photoelectrocatalytic reaction by B, F-TiO 2 NTAs, which was 46% higher than that under the photocatalysis process. Moreover, the maximum degradation rate was achieved at pH of 6 in 0.01 M of Na 2 SO 4 electrolyte solution under a current of 0.02 A and visible light for 2 h in the presence of B, F-TiO 2 NTAs. These results showed that B, F-TiO 2 NTAs exhibit remarkable photoelectrocatalytic activity in degradation of atrazine.

High solar-light photocatalytic activity of using Cu3Se2/rGO nanocomposites synthesized by a green co-precipitation method

NASA Astrophysics Data System (ADS)

Nouri, Morteza; Saray, Abdolali Moghaddam; Azimi, H. R.; Yousefi, Ramin

2017-11-01

Current work presents a facile, cost-effective, and green method to synthesize copper selenide nanostructures and copper selenide/graphene nanocomposites. The products were synthesized by a co-precipitation method by glycine amino acid as a green surfactant and graphene oxide (GO) sheets as a graphene source. X-ray diffraction patterns (XRD) of the products indicated that the products were Cu2Se3 with tetragonal phase. Fourier transform infrared (FTIR) spectroscopy and the XRD patterns indicated that the GO sheets were changed into reduced GO (rGO) during the synthesis process. Scanning and transmission electron microscopy (SEM and TEM) images showed the nanoparticles (NPs) that were decorated on rGO sheets had the significantly smaller size in compared to the pristine NPs. UV-vis results revealed that, the absorption peak of the products were in the visible region with a band-gap value between 1.85 eV and 1.95 eV. Finally, the products were applied as photocatalytic materials to remove Methylene Blue (MB) dye under solar-light and visible-light irradiation conditions. It was observed; the rGO had a significant role in enhancing the photocatalytic performance of the products and Cu2Se3/rGO (15%) could degrade more than 91% and 73% of MB only during 1 h under solar-light and visible-light sources, respectively.

Hydrothermal green synthesis of magnetic Fe3O4-carbon dots by lemon and grape fruit extracts and as a photoluminescence sensor for detecting of E. coli bacteria.

PubMed

Ahmadian-Fard-Fini, Shahla; Salavati-Niasari, Masoud; Ghanbari, Davood

2018-10-05

The aim of this work is preparing of a photoluminescence nanostructures for rapid detection of bacterial pathogens. Firstly, carbon dots (CDs) were synthesized by grape fruit, lemon, turmeric extracts and hydrothermal method. Then Fe 3 O 4 (magnetite) nanoparticles was achieved using these bio-compatible capping agents. Finally, magnetite-carbon dots were synthesized as a novel magnetic and photoluminescence nanocomposite. X-ray diffraction (XRD) confirms the crystallinity and phase of the products, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigate the morphology, shape and size of the magnetite, carbon dot and nanocomposites. Fourier transform infrared (FT-IR) spectroscopy shows the purity of the nanostructures. Ultraviolet-visible (UV-Vis) absorption and photo-luminescence (PL) spectroscopy show suitable photo-luminescence under ultraviolet irradiation. Vibrating sample magnetometer (VSM) shows super paramagnetic property of the product. Interestingly carbon dots were used as a non-toxic photoluminescence sensor for detecting of Escherichia coli (E. coli) bacteria. Results show quenching of photoluminescence of the CDs nanocomposite by increasing amount of E. coli bacteria. Copyright © 2018 Elsevier B.V. All rights reserved.

Ion beam induced optical and surface modification in plasmonic nanostructures

NASA Astrophysics Data System (ADS)

Singh, Udai B.; Gautam, Subodh K.; Kumar, Sunil; Hooda, Sonu; Ojha, Sunil; Singh, Fouran

2016-07-01

In present work, ion irradiation induced nanostructuring has been exploited as an efficient and effective tool for synthesis of coupled plasmonics nanostructures by using 1.2 MeV Xe ions on Au/ZnO/Au system deposited on glass substrate. The results are correlated on the basis of their optical absorption, surface morphologies and enhanced sensitivity of evolved phonon modes by using UV Visible spectroscopy, scanning electron microscopy (SEM), and Raman spectroscopy (RS), respectively. Optical absorbance spectra of plasmonic nanostructures (NSs) show a decrease in band gap, which may be ascribed to the formation of defects with ion irradiation. The surface morphology reveals the formation of percolated NSs upon ion irradiation and Rutherford backscattering spectrometry (RBS) study clearly shows the formation of multilayer system. Furthermore, RS measurements on samples are studied to understand the enhanced sensitivity of ion irradiation induced phonon mode at 573 cm-1 along with other modes. As compared to pristine sample, a stronger and pronounced evolution of these phonon modes is observed with further ion irradiation, which indicates localized surface plasmon results with enhanced intensity of phonon modes of Zinc oxide (ZnO) material. Thus, such plasmonic NSs can be used as surface enhanced Raman scattering (SERS) substrates.

Spectroscopic methods of process monitoring for safeguards of used nuclear fuel separations

NASA Astrophysics Data System (ADS)

Warburton, Jamie Lee

To support the demonstration of a more proliferation-resistant nuclear fuel processing plant, techniques and instrumentation to allow the real-time, online determination of special nuclear material concentrations in-process must be developed. An ideal materials accountability technique for proliferation resistance should provide nondestructive, realtime, on-line information of metal and ligand concentrations in separations streams without perturbing the process. UV-Visible spectroscopy can be adapted for this precise purpose in solvent extraction-based separations. The primary goal of this project is to understand fundamental URanium EXtraction (UREX) and Plutonium-URanium EXtraction (PUREX) reprocessing chemistry and corresponding UV-Visible spectroscopy for application in process monitoring for safeguards. By evaluating the impact of process conditions, such as acid concentration, metal concentration and flow rate, on the sensitivity of the UV-Visible detection system, the process-monitoring concept is developed from an advanced application of fundamental spectroscopy. Systematic benchtop-scale studies investigated the system relevant to UREX or PUREX type reprocessing systems, encompassing 0.01-1.26 M U and 0.01-8 M HNO3. A laboratory-scale TRansUranic Extraction (TRUEX) demonstration was performed and used both to analyze for potential online monitoring opportunities in the TRUEX process, and to provide the foundation for building and demonstrating a laboratory-scale UREX demonstration. The secondary goal of the project is to simulate a diversion scenario in UREX and successfully detect changes in metal concentration and solution chemistry in a counter current contactor system with a UV-Visible spectroscopic process monitor. UREX uses the same basic solvent extraction flowsheet as PUREX, but has a lower acid concentration throughout and adds acetohydroxamic acid (AHA) as a complexant/reductant to the feed solution to prevent the extraction of Pu. By examining UV-Visible spectra gathered in real time, the objective is to detect the conversion from the UREX process, which does not separate Pu, to the PUREX process, which yields a purified Pu product. The change in process chemistry can be detected in the feed solution, aqueous product or in the raffinate stream by identifying the acid concentration, metal distribution and the presence or absence of AHA. A fiber optic dip probe for UV-Visible spectroscopy was integrated into a bank of three counter-current centrifugal contactors to demonstrate the online process monitoring concept. Nd, Fe and Zr were added to the uranyl nitrate system to explore spectroscopic interferences and identify additional species as candidates for online monitoring. This milestone is a demonstration of the potential of this technique, which lies in the ability to simultaneously and directly monitor the chemical process conditions in a reprocessing plant, providing inspectors with another tool to detect nuclear material diversion attempts. Lastly, dry processing of used nuclear fuel is often used as a head-end step before solvent extraction-based separations such as UREX or TRUEX. A non-aqueous process, used fuel treatment by dry processing generally includes chopping of used fuel rods followed by repeated oxidation-reduction cycles and physical separation of the used fuel from the cladding. Thus, dry processing techniques are investigated and opportunities for online monitoring are proposed for continuation of this work in future studies.

Group 12 dithiocarbamate complexes: Synthesis, spectral studies and their use as precursors for metal sulfides nanoparticles and nanocomposites

NASA Astrophysics Data System (ADS)

Ajibade, Peter A.; Ejelonu, Benjamin C.

2013-09-01

Zn(II), Cd(II) and Hg(II) dithiocarbamate complexes have been synthesized and characterized by elemental analysis, thermogravimetric analysis, UV-Vis, FTIR, 1H- and 13C NMR spectroscopy. The complexes were thermolysed at 180 °C and used as single molecule precursors for the synthesis of HDA capped ZnS, CdS and HgS nanoparticles and polymethylmethacrylate (PMMA) nanocomposites. The optical and structural properties of the nanoparticles and nanocomposites were studied by UV-Vis, PL, XRD and SEM. The crystallites sizes of the nanoparticles varied between 3.03 and 23.45 nm. SEM and EDX analyses of the nanocomposites confirmed the presence of the nanoparticles in the polymer matrix.

Effect of solvents on sol-gel spin-coated nanostructured Al-doped ZnO thin films: a film for key optoelectronic applications

NASA Astrophysics Data System (ADS)

Kumar, K. Deva Arun; Valanarasu, S.; Kathalingam, A.; Ganesh, V.; Shkir, Mohd.; AlFaify, S.

2017-12-01

Aluminum-doped zinc oxide (AZO) thin films were deposited by sol-gel spin coating technique onto the glass substrates using different solvents such as 2-methoxyethanol, methanol, ethanol and isopropanol. Prepared films were characterized by XRD, Raman spectrum, SEM, UV-visible spectrophotometer, photoluminescence (PL) and electrical studies. XRD studies showed that all the prepared films are hexagonal wurtzite structure with polycrystalline nature oriented along (002) direction. SEM images showed uniform particles of size around 60 nm distributed regularly on to the entire glass substrate. EDX analysis confirmed the composition of grown AZO film consisting of Al, Zn and O elements. The prepared films showed highest optical transmittance 94% in the visible range and band gap 3.30 eV. PL spectra for all AZO films showed a strong UV emission peak at 387 nm. The AZO films prepared using isopropanol solvent showed high carrier concentration and low resistivity values as 1.72 × 1020 cm-3 and 2.90 × 10-3 Ω cm, respectively, with high figure of merit ( ϕ) value 8.42 × 10-3 (Ω/sq)-1.

Component Identification in Multi-Chemical Mixtures With Swept-Wavelength Resonant-Raman Spectroscopy

DTIC Science & Technology

2011-03-18

efficiency of the OPO, but ranges from up to 15 mW on target in the UV to 50 mW in the visible. This ability to illuminate a target with a broad...been back illuminated and coated for enhanced UV response. The run file which automates the collection process uses several input parameters to...analyzed by a Agilent spectrophotometer to determine absorbance characteristics of the liquid. The remaining mixture was then placed into a standard UV

Optical and structural properties of colloidal zirconia nanoparticles prepared by arc discharge in liquid

NASA Astrophysics Data System (ADS)

Peymani forooshani, Reza; Poursalehi, Reza; Yourdkhani, Amin

2018-01-01

Zirconia is one of the important ceramic materials with unique properties such as high melting point, high ionic conductivity, high mechanical properties and low thermal conductivity. Therefore, zirconia is one of the useful materials in refractories, thermal barriers, cutting tools, oxygen sensors electrolytes, catalysis, catalyst supports and solid oxide fuel cells. Recently, direct current (DC) arc discharge is extensively employed to synthesis of metal oxide nanostructures in liquid environments. The aim of this work is the synthesis of colloidal zirconia nanoparticles by DC arc discharge method in water as a medium. Arc discharge was ignited between two pure zirconium electrodes in water. Optical and structural properties of prepared colloidal nanoparticles were investigated. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and UV-visible spectroscopy, were employed for characterization of particle size, morphology, crystal structure and optical properties, respectively. SEM images demonstrate that the nanoparticles are spherical in shape with an average size lower than 38 nm. The XRD patterns of the nanoparticles were consistent with tetragonal and monoclinic zirconia crystal structures. The optical transmission spectra of the colloidal solution show optical characteristic of zirconia nanoparticles as a wide band gap semiconductor with no absorption peak in visible wavelength with the considerable amount of oxygen deficiency. Oxidation of colloidal nanoparticles in water could be explained via reaction with either dissociated oxygen from water in hot plasma region or with dissolved oxygen in water. The results provide a simple and flexible method for preparation of zirconia nanoparticles with a capability of mass production without environmental footprints.

Combined micro-Raman/UV-visible/fluorescence spectrometer for high-throughput analysis of microsamples.

PubMed

Noh, Jermim; Suh, Yung Doug; Park, Yong Ki; Jin, Seung Min; Kim, Soo Ho; Woo, Seong Ihl

2007-07-01

Combined micro-Raman/UV-visible (vis)/fluorescence spectroscopy system, which can evaluate an integrated array of more than 10,000 microsamples with a minimuma size of 5 microm within a few hours, has been developed for the first time. The array of microsamples is positioned on a computer-controlled XY translation microstage with a spatial resolution of 1 mum so that the spectra can be mapped with micron precision. Micro-Raman spectrometers have a high spectral resolution of about 2 cm(-1) over the wave number range of 150-3900 cm(-1), while UV-vis and fluorescence spectrometers have high spectral resolutions of 0.4 and 0.1 nm over the wavelength range of 190-900 nm, respectively. In particular, the signal-to-noise ratio of the micro-Raman spectroscopy has been improved by using a holographic Raman grating and a liquid-nitrogen-cooled charge-coupled device detector. The performance of the combined spectroscopy system has been demonstrated by the high-throughput screening of a combinatorial ferroelectric (i.e., BaTi(x)Zr(1-x)O(3)) library. This system makes possible the structure analysis of various materials including ferroelectrics, catalysts, phosphors, polymers, alloys, and so on for the development of novel materials and the ultrasensitive detection of trace amounts of pharmaceuticals and diagnostic agents.

Structural characterization, surface characteristics and non covalent interactions of a heterocyclic Schiff base: Evaluation of antioxidant potential by UV-visible spectroscopy and DFT

NASA Astrophysics Data System (ADS)

Chithiraikumar, S.; Gandhimathi, S.; Neelakantan, M. A.

2017-06-01

A heterocyclic Schiff base, (E)-4-(1-((pyridin-2-ylmethyl)imino)ethyl)benzene-1,3-diol (L) was synthesized and isolated as single crystals. Its structure was characterized by FT-IR, UV, 1H and 13C NMR, and further confirmed by X-ray crystallography. Qualitatively and quantitatively the various interactions in the crystal structure of L has been analyzed by Hirshfeld surfaces and 2D fingerprint plots. Non covalent interactions have been studied by electron localization function (ELF) and mapped with reduced density gradient (RDG) analysis. The molecular structure was studied computationally by DFT-B3LYP/6-311G(d,p) calculations. HOMO-LUMO energy levels, chemical reactivity descriptors and thermodynamic parameters have been investigated at the same level of theory. The antioxidant potential of L was evaluated experimentally by measuring DPPH free radical scavenging effect using UV-visible spectroscopy and theoretically by DFT. Theoretical parameters, such as bond dissociation enthalpy (BDE) and spin density calculated suggests that antioxidant potential of L is due to H atom abstraction from the sbnd OH group.

Green synthesis of silver nanoparticles using Alternanthera dentata leaf extract at room temperature and their antimicrobial activity.

PubMed

Kumar, Deenadayalan Ashok; Palanichamy, V; Roopan, Selvaraj Mohana

2014-06-05

A green rapid biogenic synthesis of silver nanoparticles AgNPs using Alternanthera dentata (A. dentata) aqueous extract was demonstrated in this present study. The formation of silver nanoparticles was confirmed by Surface Plasmon Resonance (SPR) at 430nm using UV-visible spectrophotometer. The reduction of silver ions to silver nanoparticles by A. dentata extract was completed within 10min. Synthesized nanoparticles were characterized using UV-visible spectroscopy; Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM). The extracellular silver nanoparticles synthesis by aqueous leaf extract demonstrates rapid, simple and inexpensive method comparable to chemical and microbial methods. The colloidal solution of silver nanoparticles were found to exhibit antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia and, Enterococcus faecalis. Copyright © 2014 Elsevier B.V. All rights reserved.

Structural, optical and dielectric properties of Sn0.97Ce0.03O2 nanostructures

NASA Astrophysics Data System (ADS)

Ahmed, Ateeq; Siddique, M. Naseem; Ali, Tinku; Tripathi, P.

2018-05-01

In present work, 3% cerium doped SnO2 (Sn0.97Ce0.03O2) nanoparticles (NPs) have been synthesized by sol-gel method. The prepared sample has been characterized by using various techniques such as XRD, UV-visible absorption spectroscopy and LCR meter measurements. Structural Rietveld refinement of XRD data reveals that (Sn0.97Ce0.03O2) sample has a pure single phase tetragonal structure with space group (P42/mnm) without creating any impurity phase such as cerium oxide. UV-visible spectroscopy determines band gap value 3.47 eV for (Sn0.97Ce0.03O2) NPs using Tauc's relation. Dielectric constant and loss decreased with increase in frequency while ac conductivity was found to increase with increase in frequency. The observed dielectric results has been explained in the light of Maxwell-Wagner model.

Pt deposited TiO2 catalyst fabricated by thermal decomposition of titanium complex for solar hydrogen production

NASA Astrophysics Data System (ADS)

Truong, Quang Duc; Le, Thanh Son; Ling, Yong-Chien

2014-12-01

C, N codoped TiO2 catalyst has been synthesized by thermal decomposition of a novel water-soluble titanium complex. The structure, morphology, and optical properties of the synthesized TiO2 catalyst were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of the Pt deposited TiO2 catalysts synthesized at different temperatures was evaluated by means of hydrogen evolution reaction under both UV-vis and visible light irradiation. The investigation results reveal that the photocatalytic H2 evolution rate strongly depended on the crystalline grain size as well as specific surface area of the synthesized catalyst. Our studies successfully demonstrate a simple method for the synthesis of visible-light responsive Pt deposited TiO2 catalyst for solar hydrogen production.

Laser-Induced Breakdown Spectroscopy: Capabilities and Applications

DTIC Science & Technology

2010-07-01

substances such as drugs, counterfeit goods, and laundered money . It may even be possible to pinpoint specific manufacturing facilities based on...point detection or standoff mode operation. LIBS used in conjunction with broadband detectors (ultraviolet [ UV ]-visible[VIS]-near-infrared[NIR] spectral...lines in the UV -VIS-NIR spectral range. Although most early LIBS applications involved metal targets, LIBS has recently been applied to a variety

Detection of elemental mercury by multimode diode laser correlation spectroscopy.

PubMed

Lou, Xiutao; Somesfalean, Gabriel; Svanberg, Sune; Zhang, Zhiguo; Wu, Shaohua

2012-02-27

We demonstrate a method for elemental mercury detection based on correlation spectroscopy employing UV laser radiation generated by sum-frequency mixing of two visible multimode diode lasers. Resonance matching of the multimode UV laser is achieved in a wide wavelength range and with good tolerance for various operating conditions. Large mode-hops provide an off-resonance baseline, eliminating interferences from other gas species with broadband absorption. A sensitivity of 1 μg/m3 is obtained for a 1-m path length and 30-s integration time. The performance of the system shows promise for mercury monitoring in industrial applications.

Intercalation of anionic organic ultraviolet ray absorbers into layered zinc hydroxide nitrate.

PubMed

Cursino, Ana Cristina Trindade; Gardolinski, José Eduardo Ferreira da Costa; Wypych, Fernando

2010-07-01

Layered zinc hydroxide nitrate (ZHN) was synthesized and nitrate ions were topotactically exchanged with three different anionic species of commercial organic ultraviolet (UV) ray absorbers: 2-mercaptobenzoic acid, 2-aminobenzoic acid, and 4-aminobenzoic acid. The exchange reactions were confirmed by X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR), ultraviolet visible (UV-Vis) spectroscopy, and thermal analysis (thermogravimetry, TGA, and differential thermal analysis, DTA). In all the anionic exchanged products, evidence of grafting of the organic species onto the inorganic matrix was obtained. In general, after intercalation/grafting, the UV absorption ability was improved in relation to the use of the parent organic material, showing that layered hydroxide salts (LHS) can be good alternative matrixes for the immobilization of organic species with UV-blocking properties in cosmetic products. Copyright 2010 Elsevier Inc. All rights reserved.

Synthesis and Characterization of Photocatalytic TiO 2 -ZnFe 2 O 4 Nanoparticles

DOE PAGES

Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

2006-01-01

A new coprecipimore » tation/hydrolysis synthesis route is used to create a TiO 2 -ZnFe 2 O 4 nanocomposite that is directed towards extending the photoresponse of TiO 2 from UV to visible wavelengths ( > 400   nm ). The effect of TiO 2 's accelerated anatase-rutile phase transformation due to the presence of the coupled ZnFe 2 O 4 narrow-bandgap semiconductor is evaluated. The transformation's dependence on pH, calcinations temperature, particle size, and ZnFe 2 O 4 concentration has been analyzed using XRD, SEM, and UV-visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in a ZnFe 2 O 4 nanocomposite are outlined. The visible-light-activated photocatalytic activity of the TiO 2 -ZnFe 2 O 4 nanocomposites has been compared to an Aldrich TiO 2 reference catalyst, using a solar-simulated photoreactor for the degradation of phenol.« less

Investigation of the Structure, Optical and Electrical Properties of Lithium Perchlorate Doped Polyaniline Composite: Aloe Vera Used as a Bio-Plasticizer

NASA Astrophysics Data System (ADS)

Yesappa, L.; Niranjana, M.; Ashokkumar, S. P.; Vijeth, H.; Sharanappa, Chapi; Raghu, S.; Devendrappa, H.

2017-12-01

Bio-plasticizer based polyaniline (PANI)/lithium perchlorate (LiClO4) composites were synthesized by the facile in situ method. The composites were characterized using the Fourier transform infrared spectroscopy (FT-IR) to identify the chemical interactions. A band appeared at 1502 cm-1 due to the presence of the -H2CO- group and CH2 scissor mode vibration for the PAL15% composite. This considerable change in the morphology of LiClO4 homogeneous dispersion in a PANI matrix was investigated by scanning electron microscopy (SEM). The UV-Visible absorption (UV-Vis) showed 300-400 nm attributed to the π- π* transition and exhibited a red shift from 535 nm to 617 nm in the visible region, indicating a decrease in band gap. The variations in dielectric constant with the addition of lithium perchlorate (LiClO4) at different temperatures and in the frequency range of 20 Hz-1 MHz were assessed through impedance analysis. The temperature dependent electrical conductivity increased with increasing temperature as well as dopant concentration. High conductivity of 1.41 × 10-3 S/cm corresponding to activation energy of 0.02 eV and 2.95 eV optical band gap for 15 wt.% of LiClO4 concentration was observed. The cyclic voltammetry measurement revealed a typical rectangular shape of the integral area, suggesting that the composite has strong electrochemical strength and is a possible candidate for electrochemical super capacitor and solar cell applications.

Specific behavior of the p-aminothiophenol--silver sol system in their Ultra-Violet-Visible (UV-Visible) and Surface Enhanced Raman (SERS) spectra.

PubMed

Firkala, Tamás; Tálas, Emília; Mihály, Judith; Imre, Tímea; Kristyán, Sándor

2013-11-15

The UV-Visible and Surface Enhanced Raman Spectroscopy (SERS) behavior of silver sol (a typical SERS agent) were studied in the presence of different bifunctional thiols such as p-aminothiophenol, p-mercaptobenzoic acid, p-nitrothiophenol, p-aminothiophenol hydrochloride, and 2-mercaptoethylamine hydrochloride in diluted aqueous solution. Our results confirm that the p-aminothiophenol induced aggregation of citrate stabilized silver colloid originates from its electrostatic nature, as well as the azo-bridge formation cannot be the reason of the observed time dependent UV-Visible spectra. Based on our parallel SERS and electrospray ionization mass spectrometry measurements, we have concluded that certain amount of oxidized form of the probe molecule has to be present for the so-called b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Our findings seem to support the idea that the azo-bridge formation is responsible for the b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Copyright © 2013 Elsevier Inc. All rights reserved.

Synthesis and evaluation of optical and antimicrobial properties of Ag-SnO2 nanocomposites

NASA Astrophysics Data System (ADS)

Kumar Nair, Kishore; Kumar, Promod; Kumar, Vinod; Harris, R. A.; Kroon, R. E.; Viljoen, Bennie; Shumbula, P. M.; Mlambo, M.; Swart, H. C.

2018-04-01

We report on the sol-gel based room temperature synthesis of undoped SnO2 and Ag-SnO2 nanostructures. The synthesized nanostructures were characterized by Fourier transform infrared spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, High-resolution transmission electron microscopy (HR-TEM) and UV-visible spectroscopy. The XRD pattern confirmed that the obtained nanostructures have a tetragonally rutile structure. No extra phase changes were observed after Ag doping. UV-visible spectroscopy measurements indicated that the band gap of 3.59 eV for pure SnO2 nanostructures, decreased to 3.39 eV after doping. TEM analysis showed that no regular shape morphology existed and some rod-shaped particles were also detected in the nanostructures. The antibacterial activity of the nanostructures against E. coli was evaluated and a continuous decrease of microbial count was observed. The microbial population decreased from 6 × 105 cfu/ml to 7 × 104 cfu/ml and 5 × 104 cfu/ml on SnO2 and Ag-SnO2 treatments, respectively. Thus, the nanostructures can be used for the biorational management of E. coli for waste water treatment before discharge.

Gigantol from Dendrobium chrysotoxum Lindl. binds and inhibits aldose reductase gene to exert its anti-cataract activity: An in vitro mechanistic study.

PubMed

Wu, Jie; Li, Xue; Wan, Wencheng; Yang, Qiaohong; Ma, Weifeng; Chen, Dan; Hu, Jiangmiao; Chen, C-Y Oliver; Wei, Xiaoyong

2017-02-23

Dendrobium. chrysotoxum Lindl is a commonly used species of medicinal Dendrobium which belongs to the family of Orchidaceae, locally known as "Shihu" or "Huangcao". D. chrysotoxum Lindl is widely known for medicinal values in traditional Chinese medicine as it possesses anti-inflammatory, anti-hyperglycemic induction, antitumor and antioxidant properties. To characterize the interaction between gigantol extracted from D. chrysotoxum Lindl and the AR gene, and determine gigantol's efficacy against cataractogenesis. Human lens epithelial cells (HLECs) were induced by glucose as the model group. Reverse transcription polymerase chain reaction (RT-PCR) was used to assess AR gene expression. Then, the mode of interaction of gigantol with the AR gene was evaluated by UV-visible spectroscopy, atomic force microscope (AFM) and surface-enhanced Raman spectroscopy (SERS). The binding constant was determined by UV-visible. Gigantol depressed AR gene expression in HLECs. UV-visible spectra preliminarily indicated that interaction between the AR gene and gigantol may follow the groove mode, with a binding constant of 1.85×10 3 L/mol. Atomic force microscope (AFM) data indicated that gigantol possibly bound to insert AR gene base pairs of the double helix. Surface-enhanced Raman spectroscopy (SERS) studies further supported these observations. Gigantol extracted from D. chrysotoxum Lindl not only has inhibitory effects on aldose reductase, but also inhibits AR gene expression. These findings provide a more comprehensive theoretical basis for the use of Dendrobium for the treatment of diabetic cataract. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Plasmon-resonance-enhanced visible-light photocatalytic activity of Ag quantum dots/TiO2 microspheres for methyl orange degradation

NASA Astrophysics Data System (ADS)

Yu, Xin; Shang, Liwei; Wang, Dongjun; An, Li; Li, Zhonghua; Liu, Jiawen; Shen, Jun

2018-06-01

We successfully prepared Ag quantum dots modified TiO2 microspheres by facile solvothermal and calcination method. The as-prepared Ag quantum dots/TiO2 microspheres were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The Ag quantum dots/TiO2 photocatalyst showed excellent visible light absorption and efficient photocatalytic activity for methyl orange degradation. And the sample with the molar ratio of 0.05 (Ag to Ti) showed the best visible light photocatalytic activity for methyl orange degradation, mainly because of the surface plasmon resonance (SPR) effects of Ag quantum dots to generate electron and hole pairs for enhanced visible light photocatalysis. Finally, possible visible light photocatalytic mechanism of Ag quantum dots/TiO2 microspheres for methyl orange degradation was proposed in detail.

Large-scale preparation of shape controlled SnO and improved capacitance for supercapacitors: from nanoclusters to square microplates

NASA Astrophysics Data System (ADS)

Wang, Lu; Ji, Hongmei; Zhu, Feng; Chen, Zhi; Yang, Yang; Jiang, Xuefan; Pinto, João; Yang, Gang

2013-07-01

Here, we first provide a facile ultrasonic-assisted synthesis of SnO using SnCl2 and the organic solvent of ethanolamine (ETA). The moderate alkalinity of ETA and ultrasound play very important roles in the synthesis of SnO. After the hydrolysis of the intermediate of ETA-Sn(ii), the as-synthesized SnO nanoclusters undergo assembly, amalgamation, and preferential growth to microplates in hydrothermal treatment. The as-synthesized SnO was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible absorption spectroscopy (UV-vis) and X-ray diffraction (XRD). To explore its potential applications in energy storage, SnO was fabricated into a supercapacitor electrode and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge measurements. The as-synthesized SnO exhibits remarkable pseudocapacitive activity including high specific capacitance (208.9 F g-1 at 0.1 A g-1), good rate capability (65.8 F g-1 at 40 A g-1), and excellent cycling stability (retention 119.3% after 10 000 cycles) for application in supercapacitors. The capacitive behavior of SnO with various crystal morphologies was observed by fitted EIS using an equivalent circuit. The novel synthetic route for SnO is a convenient and potential way to large-scale production of microplates which is expected to be applicable in the synthesis of other metal oxide nanoparticles.Here, we first provide a facile ultrasonic-assisted synthesis of SnO using SnCl2 and the organic solvent of ethanolamine (ETA). The moderate alkalinity of ETA and ultrasound play very important roles in the synthesis of SnO. After the hydrolysis of the intermediate of ETA-Sn(ii), the as-synthesized SnO nanoclusters undergo assembly, amalgamation, and preferential growth to microplates in hydrothermal treatment. The as-synthesized SnO was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible absorption spectroscopy (UV-vis) and X-ray diffraction (XRD). To explore its potential applications in energy storage, SnO was fabricated into a supercapacitor electrode and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge measurements. The as-synthesized SnO exhibits remarkable pseudocapacitive activity including high specific capacitance (208.9 F g-1 at 0.1 A g-1), good rate capability (65.8 F g-1 at 40 A g-1), and excellent cycling stability (retention 119.3% after 10 000 cycles) for application in supercapacitors. The capacitive behavior of SnO with various crystal morphologies was observed by fitted EIS using an equivalent circuit. The novel synthetic route for SnO is a convenient and potential way to large-scale production of microplates which is expected to be applicable in the synthesis of other metal oxide nanoparticles. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00951c

Photocatalytic removal of doxycycline from aqueous solution using ZnO nano-particles: a comparison between UV-C and visible light.

PubMed

Pourmoslemi, Shabnam; Mohammadi, Ali; Kobarfard, Farzad; Amini, Mohsen

2016-10-01

Zinc oxide nano-particles were synthesized, characterized and used for photocatalytic degradation of doxycycline using UV-C and visible light. Effects of several operational factors including initial pH of antibiotic solution, initial antibiotic concentration and ZnO nano-particles loading amount were investigated. Comparing photocatalytic degradation and mineralization of doxycycline under UV-C and visible light showed successful application of the method under both light sources. However, reaction rate was higher under UV-C irradiation, which degraded doxycycline almost completely in 5 hours, and 68% mineralization was achieved. Synthesized ZnO nano-particles were successfully applied for photocatalytic degradation of doxycycline in a pharmaceutical wastewater sample. The process was fitted to the pseudo first order kinetic model with rate constants in the range of 6-22(×10 -3 ) mg L -1 min -1 with respect to initial concentration of doxycycline under UV-C irradiation. The Langmuir-Hinshelwood model was also employed for describing the photocatalytic reaction with surface reaction kinetic constant k c and equilibrium adsorption constant K LH values calculated as 0.12 mg L -1 min -1 and 2.2 L mg -1 , respectively. Degradation of doxycycline was followed by UV-visible spectroscopy and a validated stability indicating high-performance liquid chromatography method that was developed using stressed samples of doxycycline and could selectively determine doxycycline in the presence of its degradation products. Mass spectrometry was used for determining final degradation products.

Photochemistry of Fe:H2O Adducts in Argon Matrixes: A Combined Experimental and Theoretical Study in the Mid-IR and UV-Visible Regions.

PubMed

Deguin, Vincent; Mascetti, Joëlle; Simon, Aude; Ben Amor, Nadia; Aupetit, Christian; Latournerie, Sandra; Noble, Jennifer A

2018-01-18

The photochemistry of Fe:H 2 O adducts is of interest in fields as diverse as catalysis and astrochemistry. Industrially, iron can be used as a catalyst to convert H 2 O to H 2 , whereas in the interstellar medium it may be an important component of dust grains, influencing the chemistry on their icy surfaces. This study consisted of the deposition and spectral characterization of binary systems of atomic iron with H 2 O in cryogenic argon matrixes. In this way, we were able to obtain information about the interaction of the two species; we observed the formation of adducts of iron monomers and dimers with water molecules in the mid-IR and UV-visible spectral domains. Upon irradiation with a UV radiation source, the iron species were inserted into the water molecules to form HFeOH and HFe 2 OH, leading in some cases to the formation of FeO possibly accompanied by the production of H 2 . DFT and correlated multireference wave function calculations confirmed our attributions. This combination of IR and UV-visible spectroscopy with theoretical calculations allowed us to determine, for the first time, the spectral characteristics of iron adducts and their photoproducts in the UV-visible and in the OH stretching region of the mid-IR domain.

The effect of Low Earth Orbit exposure on some experimental fluorine and silicon-containing polymers

NASA Technical Reports Server (NTRS)

Connell, John W.; Young, Philip R.; Kalil, Carol G.; Chang, Alice C.; Siochi, Emilie J.

1994-01-01

Several experimental fluorine and silicon-containing polymers in film form were exposed to low Earth orbit (LEO) on a Space Shuttle flight experiment (STS-46, Evaluation of Oxygen Interaction with Materials, EOIM-3). The environmental parameters of primary concern were atomic oxygen (AO) and ultraviolet (UV) radiation. The materials were exposed to 2.3 plus or minus 0.1 x 10(exp 20) oxygen atoms/sq cm and 30.6 UV sun hours during the flight. In some cases, the samples were exposed at ambient, 120 C and 200 C. The effects of exposure on these materials were assessed utilizing a variety of characterization techniques including optical, scanning electron (SEM) and scanning tunneling (STM) microscopy, UV-visible (UV-VIS) transmission, diffuse reflectance infrared (DR-FTIR), x-ray photoelectron (XPS) spectroscopy, and in a few cases, gel permeation chromatography (GPC). In addition, weight losses of the films, presumably due to AO erosion, were measured. The fluorine-containing polymers exhibited significant AO erosion and exposed films were diffuse or 'frosted' in appearance and consequently displayed dramatic reductions in optical transmission. The silicon-containing films exhibited minimum AO erosion and the optical transmission of exposed films was essentially unchanged. The silicon near the exposed surface in the films was converted to silicate/silicon oxide upon AO exposure which subsequently provided protection for the underlying material. The silicon-containing epoxies are potentially useful as AO resistant coatings and matrix resins as they are readily processed into carbon fiber reinforced composites and cured via electron radiation.

UV/vis and NIR light-responsive spiropyran self-assembled monolayers.

PubMed

Ivashenko, Oleksii; van Herpt, Jochem T; Feringa, Ben L; Rudolf, Petra; Browne, Wesley R

2013-04-02

Self-assembled monolayers of a 6-nitro BIPS spiropyran (SP) modified with a disulfide-terminated aliphatic chain were prepared on polycrystalline gold surfaces and characterized by UV/vis absorption, surface-enhanced Raman scattering (SERS), and X-ray photoelectron spectroscopies (XPS). The SAMs obtained are composed of the ring-closed form (i.e., spiropyran) only. Irradiation with UV light results in conversion of the monolayer to the merocyanine form (MC), manifested in the appearance of an N(+) contribution in the N 1s region of the XPS spectrum of the SAMs, the characteristic absorption band of the MC form in the visible region at 555 nm, and the C-O stretching band in the SERS spectrum. Recovery of the initial state of the monolayer was observed both thermally and after irradiation with visible light. Several switching cycles were performed and monitored by SERS spectroscopy, demonstrating the stability of the SAMs during repeated switching between SP and MC states. A key finding in the present study is that ring-opening of the surface-immobilized spiropyrans can be induced by irradiation with continuous wave NIR (785 nm) light as well as by irradiation with UV light. We demonstrate that ring-opening by irradiation at 785 nm proceeds by a two-photon absorption pathway both in the SAMs and in the solid state. Hence, spiropyran SAMs on gold can undergo reversible photochemical switching from the SP to the MC form with both UV and NIR and the reverse reaction induced by irradiation with visible light or heating. Furthermore, the observation of NIR-induced switching with a continuous wave source holds important consequences in the study of photochromic switches on surfaces using SERS and emphasizes the importance of the use of multiple complementary techniques in characterizing photoresponsive SAMs.

Porous Silicon Covered with Silver Nanoparticles as Surface-Enhanced Raman Scattering (SERS) Substrate for Ultra-Low Concentration Detection.

PubMed

Kosović, Marin; Balarin, Maja; Ivanda, Mile; Đerek, Vedran; Marciuš, Marijan; Ristić, Mira; Gamulin, Ozren

2015-12-01

Microporous and macro-mesoporous silicon templates for surface-enhanced Raman scattering (SERS) substrates were produced by anodization of low doped p-type silicon wafers. By immersion plating in AgNO3, the templates were covered with silver metallic film consisting of different silver nanostructures. Scanning electron microscopy (SEM) micrographs of these SERS substrates showed diverse morphology with significant difference in an average size and size distribution of silver nanoparticles. Ultraviolet-visible-near-infrared (UV-Vis-NIR) reflection spectroscopy showed plasmonic absorption at 398 and 469 nm, which is in accordance with the SEM findings. The activity of the SERS substrates was tested using rhodamine 6G (R6G) dye molecules and 514.5 nm laser excitation. Contrary to the microporous silicon template, the SERS substrate prepared from macro-mesoporous silicon template showed significantly broader size distribution of irregular silver nanoparticles as well as localized surface plasmon resonance closer to excitation laser wavelength. Such silver morphology has high SERS sensitivity that enables ultralow concentration detection of R6G dye molecules up to 10(-15) M. To our knowledge, this is the lowest concentration detected of R6G dye molecules on porous silicon-based SERS substrates, which might even indicate possible single molecule detection.

A spirooxazine derivative as a highly sensitive cyanide sensor by means of UV-visible difference spectroscopy.

PubMed

Zhu, Shaoyin; Li, Minjie; Sheng, Lan; Chen, Peng; Zhang, Yumo; Zhang, Sean Xiao-An

2012-12-07

A spirooxazine derivative 2-nitro-5a-(2-(4-dimethylaminophenyl)-ethylene)-6,6-dimethyl-5a,6-dihydro-12H-indolo[2,1-b][1,3]benzooxazine (P1) was explored as a sensitive cyanide probe. Different from conventional spiropyrans, P1 avoided locating the 3H-indolium cation and the 4-nitrophenolate anion in the same conjugated structure, which enhanced the positive charge of 3H-indolium cation so that the sensitivity and reaction speed were improved highly. UV-visible difference spectroscopy using P1 detection solution as a timely reference improved the measurement accuracy, prevented the error caused by the inherent absorption change of P1 solution with time. This enabled the "positive-negative alternative absorption peaks" in difference spectrum to be used as a finger-print to distinguish whether the spectral change was caused by cyanide. Benefiting from the special design of the molecular structure and the strategy of difference spectroscopy, P1 showed high selectivity and sensitivity for CN(-). A detection limit of 0.4 μM and a rate constant of 1.1 s(-1) were achieved.

Development of Polythiophene/Acrylonitrile-Butadiene Rubbers for Artificial Muscle

NASA Astrophysics Data System (ADS)

Thipdech, Pacharavalee; Sirivat, Anuvat

2007-03-01

Electroactive polymers (EAPs) can respond to the applied electrical field by an extension or a retraction. In this work, we are interested in using an elastomeric blend for electroactive applications, acrylonitirle-butadiene rubber (NBR) containing a conductive polymer (Poly(3-thiopheneacetic acid, PTAA); the latter can be synthesized via oxidative polymerization. FT-IR, Thermogravimetric analysis (TGA), ^1H-NMR, UV-visible spectroscopy, and SEM are used to characterize the conductive polymer. Electrorheological properties are measured and investigated in terms of acrylonitrile content, blending ratio, doping level, and temperature. Experiments are carried out under oscillatory shear mode and with applied electric field strength varying from 0 to 2 kV/mm. Dielectric properties, conductivities are measured and correlated with the storage modulus responses. The storage modulus sensitivity, δG'G'0of the pure rubbers increases with increasing electric field strength. They attain the maximum values of about 30% and become constant at electric strength at and above 1000 V/mm.

LPG ammonia and nitrogen dioxide gas sensing properties of nanostructured polypyrrole thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bagul, Sagar B., E-mail: nano.sbbagul@gmail.com; Upadhye, Deepak S.; Sharma, Ramphal, E-mail: rps.phy@gmail.com

Nanostructured Polypyrrole thin film was synthesized by easy and economic chemical oxidative polymerization technique on glass at room temperature. The prepared thin film of Polypyrrole was characterized by optical absorbance study by UV-visible spectroscopy and electrical study by I-V measurement system. The optical absorbance spectrum of Polypyrrole shows two fundamental peaks in region of 420 and 890 nm, which confirms the formation of Polypyrrole on glass substrate. The I-V graph of nanostructured Polypyrrole represents the Ohmic nature. Furthermore, the thin film of Polypyrrole was investigated by Scanning electron microscopy for surface morphology study. The SEM micrograph represents spherical nanostructured morphology ofmore » Polypyrrole on glass substrate. In order to investigate gas sensing properties, 100 ppm of LPG, Ammonia and Nitrogen Dioxide were injected in the gas chamber and magnitude of resistance has been recorded as a function of time in second. It was observed that nanostructured Polypyrrole thin film shows good sensing behavior at room temperature.« less

Influence of Fe ions on structural, optical and thermal properties of SnO{sub 2} nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmed, Ateeq, E-mail: ateeqamu124@gmail.com; Tripathi, P.; Khan, Wasi

2016-05-23

In the present work, Fe doped SnO{sub 2} nanoparticles with the composition Sn{sub 1-x}Fe{sub x}O{sub 2} (x = 0, 0.02, 0.04 and 0.06) have been successfully synthesized using sol-gel auto combustion technique. The samples are characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Ultraviolet (UV-Visible) absorption spectroscopy and thermal gravimetric analysis (TGA). The XRD study shows that all the samples have been found in tetragonal rutile structure without any extra phase and average crystallite size which lies in the range of 6-17 nm. The EDAX spectrum confirmed the doping of Fe ion into tin oxidemore » nanomaterial. The optical band gap of doped SnO{sub 2} is found to decrease with increasing Fe ion concentration, which is due to the formation of donor energy levels in the actual band gap of SnO{sub 2}.« less

Effect of Host Media on Microbial Influenced Corrosion due to Desulfotomaculum nigrificans

NASA Astrophysics Data System (ADS)

Lata, Suman; Sharma, Chhaya; Singh, Ajay K.

2013-04-01

This article reports about the tests carried to investigate microbial-induced corrosion on stainless steels due to sulfate-reducing bacteria sp. Desulfotomaculum nigrificans in different host media. Stainless steel 304L, 316L, and 2205 were selected for the test. Modified Baar's media (BM), sodium chloride solution, and artificial sea water (SW) were used as test solutions in anaerobic conditions. Electrochemical polarization and immersion test were performed to estimate the extent of corrosion rate and pitting on stainless steels. SEM/EDS were used to study the details inside/outside pits formed on the corroded samples. Biofilm formed on corroded coupons was analyzed for its components by UV/Visible spectroscopy. Corrosion attack on the test samples was observed maximum in case of exposure to SW followed by NaCl solution, both having sulfide and chloride whereas stainless steel exposed to BM, having sulfide, showed minimum attack. Tendency of extracellular polymeric substances to bind metal ions is observed to be responsible for governing the extent of corrosion attack.

The optical and structural properties of graphene nanosheets and tin oxide nanocrystals composite

NASA Astrophysics Data System (ADS)

Farheen, Parveen, Azra; Azam, Ameer

2018-05-01

A nanocomposite material consisting of metal oxide and reduced graphene oxide was prepared via simple, economic, and effective chemical reduction method. The synthesis strategy was based on the reduction of GO with Sn2+ ion that combines tin oxidation and GO reduction in one step, which provides a simple, low-cost and effective way to prepare graphene nanosheets/SnO2 nanocrystals composites because no additional chemicals were needed. SEM and TEM images shows the uniform distribution of the SnO2 nanocrystals on the Graphene nanosheets (GNs) surface and transmission electron microscope shows an average particle size of 2-4 nm. The mean crystallite size was calculated by Debye Scherrer formula and was found to be about 4.0 nm. Optical analysis was done by using UV-Visible spectroscopy technique and the band gap energy of the GNs/SnO2 nanocomposite was calculated by Tauc relation and came out to be 3.43eV.

Diatomite-immobilized BiOI hybrid photocatalyst: Facile deposition synthesis and enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Li, Baoying; Huang, Hongwei; Guo, Yuxi; Zhang, Yihe

2015-10-01

A novel diatomite-immobilized BiOI hybrid photocatalyst has been prepared by a facile one-step deposition process for the first time. The structure, morphology and optical property of the products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic performance of the as-prepared BiOI/diatomite photocatalysts was studied by photodegradation of Rhodamine B (RhB) and methylene blue (MB) and monitoring photocurrent generation under visible light (λ > 420 nm). The results revealed that BiOI/diatomite composites exhibit enhanced photocatalytic activity compared to the pristine BiOI sample. This enhancement should be attributed to that diatomite can play as an excellent carrier platform to increase the reactive sites and promote the separation of photogenerated electron-hole pairs. In addition, the corresponding photocatalytic mechanism was proposed based on the active species trapping experiments. This work shed new light on facile fabrication of novel composite photocatalyst based on natural mineral.

Structure and optical properties of ZnO produced from microwave hydrothermal hydrolysis of tris(ethylenediamine)zinc nitrate complex

NASA Astrophysics Data System (ADS)

Mostafa, Nasser Y.; Heiba, Zein K.; Ibrahim, Mohamed M.

2015-01-01

ZnO powders were synthesized using a solution microwave hydrothermal hydrolysis process and tris(ethylenediamine)zinc nitrate {[Zn(en)3](NO3)2} (en = ethylenediamine) as a precursor. Hydrolysis of the precursor complex at different pH produced zinc oxide with a diversity of well-defined morphologies. The effect of hydrolysis pH values on the structural and optical properties has been explored using XRD, SEM, and UV-visible diffuse reflectance spectroscopy (DRS). At pH = 7.0, randomly dispersed rods were formed. Whereas flower-like morphologies were obtained by treating the complex precursor in water at pH = 10.0 and 12.0. The ZnO4 tetrahedrons are greatly affected by the pH value. The band gap decreased sharply with increasing the pH value from 7.0 to 10.0, then slightly decreased with further increasing the pH to 12.0. The relationship between band gap and both structure and surface defects of the samples is also discussed.

Utility of charge-transfer complexation for the assessment of macrocyclic polyethers: Spectroscopic, thermal and surface morphology characteristics of two highly crown ethers complexed with acido acceptors

NASA Astrophysics Data System (ADS)

Refat, Moamen S.; Adam, Abdel Majid A.; Saad, Hosam A.

2015-04-01

The study of the complexing ability of macrocyclic compounds to organic and inorganic substances is of great interest. The aim of this work is to provide basic data that can be used to the assessment of macrocyclic crown ethers quantitatively based on charge-transfer (CT) complexation. This goal was achieved by preparing CT complexes of two interesting mixed nitrogen-oxygen crown ethers with acido acceptors (chloranilic and picric acid), which were fully structurally characterized. The crown ethers are 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane (HDHC) and 1,4,10-trioxa-7,13-diaza-cyclopentadecane (TDPD). The obtained complexes were structurally characterized via elemental analysis, IR, Raman, 1H NMR, and UV-visible spectroscopy. Thermal properties of these complexes were also studied, and their kinetic thermodynamic parameters were calculated. Furthermore, the microstructure properties of these complexes have also been investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM).

LPG ammonia and nitrogen dioxide gas sensing properties of nanostructured polypyrrole thin film

NASA Astrophysics Data System (ADS)

Bagul, Sagar B.; Upadhye, Deepak S.; Sharma, Ramphal

2016-05-01

Nanostructured Polypyrrole thin film was synthesized by easy and economic chemical oxidative polymerization technique on glass at room temperature. The prepared thin film of Polypyrrole was characterized by optical absorbance study by UV-visible spectroscopy and electrical study by I-V measurement system. The optical absorbance spectrum of Polypyrrole shows two fundamental peaks in region of 420 and 890 nm, which confirms the formation of Polypyrrole on glass substrate. The I-V graph of nanostructured Polypyrrole represents the Ohmic nature. Furthermore, the thin film of Polypyrrole was investigated by Scanning electron microscopy for surface morphology study. The SEM micrograph represents spherical nanostructured morphology of Polypyrrole on glass substrate. In order to investigate gas sensing properties, 100 ppm of LPG, Ammonia and Nitrogen Dioxide were injected in the gas chamber and magnitude of resistance has been recorded as a function of time in second. It was observed that nanostructured Polypyrrole thin film shows good sensing behavior at room temperature.

Forensic practice in the field of protection of cultural heritage

NASA Astrophysics Data System (ADS)

Kotrlý, Marek; Turková, Ivana

2012-06-01

Microscopic methods play a key role in issues covering analyses of objects of art that are used on the one hand as screening ones, on the other hand they can lead to obtaining data relevant for completion of expertise. Analyses of artworks, gemmological objects and other highly valuable commodities usually do not rank among routine ones, but every analysis is specific, be it e.g. material investigation of artworks, historical textile materials and other antiques (coins, etc.), identification of fragments (from transporters, storage places, etc.), period statues, sculptures compared to originals, analyses of gems and jewellery, etc. A number of analytical techniques may be employed: optical microscopy in transmitted and reflected light, polarization and fluorescence in visible, UV and IR radiation; image analysis, quantitative microspectrophotometry; SEM/EDS/WDS; FTIR and Raman spectroscopy; XRF and microXRF, including mobile one; XRD and microXRD; x-ray backlight or LA-ICP-MS, SIMS, PIXE; further methods of organic analysis are also utilised - GS-MS, MALDI-TOF, etc.

Synthesis of BiOCl nanosheets with oxygen vacancies for the improved photocatalytic properties

NASA Astrophysics Data System (ADS)

Cai, Yujie; Li, Dongya; Sun, Jingyu; Chen, Mengdie; Li, Yirui; Zou, Zhongwei; Zhang, Hua; Xu, Haiming; Xia, Dongsheng

2018-05-01

The square-sharped BiOCl nanosheets with oxygen vacancies were successfully synthesized via a facile hydrothermal route using xylitol as surfactant. The as-prepared BiOCl samples were characterized by Powder X-ray Diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), UV-Vis diffuse reflectance spectra (DRS), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) and Electron spin resonance (ESR). The as-prepared samples were phase-pure with the width and the thickness were about 50-400 nm and 20-50 nm respectively. Besides, the photodegradation performances showed the BiOCl nanosheets with 0.1 g concentration of xylitol (BOC-1) had the best photocatalytic activity under visible light due to its special polycrystalline structure, grain boundary and an optimum concentration of oxygen vacancies. The h+ and radO2- were the two main active species during the photocatalytic process and the possible photocatalytic mechanism was proposed.

The green synthesis of fine particles of gold using an aqueous extract of Monotheca buxifolia (Flac.)

NASA Astrophysics Data System (ADS)

Anwar, Natasha; Khan, Abbas; Shah, Mohib; Azam, Andaleeb; Zaman, Khair; Parven, Zahida

2016-12-01

This study deals with the synthesis and physicochemical investigation of gold nanoparticles using an aqueous extract of Monotheca buxifolia (Flac.). On the treatment of aqueous solution of tetrachloroauric acid with the plant extract, gold nanoparticles were rapidly fabricated. The synthesized particles were characterized by UV-Vis spectrophotometry (UV), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX) and Scanning electron microscopy (SEM). The formation of AuNPs was confirmed by noting the change in color through visual observations as well as via UV-Vis spectroscopy. UV‒Vis spectrum of the aqueous medium containing gold nanoparticles showed an absorption peak at around 540 nm. FTIR was used to identify the chemical composition of gold nanoparticles and Au-capped plant extract. The presence of elemental gold was also confirmed through EDX analysis. SEM analysis of the gold nanoparticles showed that they have a uniform spherical shape with an average size in the range of 70-78 nm. This green system showed to be better capping and stabilizing agent for the fine particles. Further, the antioxidant activity of Monotheca buxifolia (Flac.) extract and Au-capped with the plant extract was also evaluated using FeCl3/K3[Fe(CN)]6 in vitro assay.

Photochemical Study of Silver Nanoparticles Formed from the Reduction of Silver Ions by Humic Acid

NASA Astrophysics Data System (ADS)

Leslie, Renee M.

This study focuses on the ability of silver ions and humic acid to form silver nanoparticles in the presence of UV and visible light. Silver nanoparticles have a number of industrial applications due primarily to their antimicrobial properties, but these properties pose an environmental threat. Silver nanoparticles can directly disrupt sensitive ecosystems by harming bacteria. Consumption of silver nanoparticles results in silver ions and silver nanoparticles entering waterways; the presence of silver ions raises the question of whether nanoparticles can reform in environmental waters. As our data show, silver nanoparticles can form from the reduction of silver ions by humic acid after irradiation with UV and visible light. In order to better understand the mechanism of these naturally synthesized silver nanoparticles, we investigated the effects of reactant concentration, experimental conditions and presence of ions/reactive species. We monitored silver nanoparticle growth with UV-visible spectroscopy. The evolution in time of nanoparticle size was monitored by dynamic light scattering (DLS).

Synthesis, characterization, temperature dependent electrical and magnetic properties of Ca3Co4O9 by a starch assisted sol-gel combustion method

NASA Astrophysics Data System (ADS)

Agilandeswari, K.; Ruban Kumar, A.

2014-09-01

In this present work we discussed the synthesis of pure Ca3Co4O9 ceramic powder by a starch assisted sol-gel combustion method. The products were characterized by powder X-ray diffraction (XRD), thermogravimetric and differential thermal analyses (TGA-DTA), Fourier transformation infrared spectroscopy (FTIR), scanning electron microscope (SEM) and UV-visible diffuse reflectance spectroscopy (DRS). X-ray diffraction pattern confirmed the formation of single phase Ca3Co4O9 at a sintering temperature of 1073 K, and it is also confirmed in the thermal analysis. SEM images indicate the presence of diffused microporous sphere like morphology and the grain sizes are in the range of 150-300 nm. Optical properties of Ca3Co4O9 ceramic show a band gap at an energy level of 2.10 eV. A maximum electrical resistivity of 0.002 mΩ cm was exhibited by Ca3Co4O9 that was decreased to 0.0012 mΩ cm, when the temperature increased from 300 K to 473 K. Dielectric studies were conducted at various temperatures from room temperature to 673 K and the results indicate that the space charge polarization contributes to the conduction mechanism. It also shows that the dielectric relaxation with activation energy is 0.96 eV. The magnetic properties as a function of temperature represent the ferri-paramagnetic phase transition at above 50 K. M-H curve shows the hysteresis loop with saturation magnetization (Ms) and confirms the presence of soft magnetic materials.

Synthesis, characterization and photocatalysis enhancement of Eu2O3-ZnO mixed oxide nanoparticles

NASA Astrophysics Data System (ADS)

Mohamed, W. S.; Abu-Dief, Ahmed M.

2018-05-01

Pure ZnO nanoparticles (NPs) and mixed Eu2O3 and ZnO NPs with different Eu2O3 ratios (5%, 10%, and 15%) were synthesized by a precipitation method under optimum conditions. The synthesized samples were characterized by means of X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and UV-vis diffuse reflectance spectroscopy. The as-synthesized ZnO NPs exhibit high phase purity and a highly crystalline wurtzite ZnO structure. The mixed Eu2O3 and ZnO NPs exhibit a Eu2O3 zinc blend phase in addition to the wurtzite phase of pure ZnO, confirming the high purity and good crystallinity of the as-synthesized samples. The high-purity formation of ZnO and Eu2O3 phases was confirmed by FTIR and Raman spectra. Microstructural analysis by SEM and TEM confirmed the sphere-like morphology with different particle sizes (29-40 nm) of the as-synthesized samples. The photocatalytic activities of pure ZnO NPs and mixed Eu2O3 and ZnO NPs for the degradation of methylene blue were evaluated under ultraviolet (UV) irradiation. The results show that Eu2O3 plays an important role in the enhancement of the photocatalytic properties of ZnO NPs. We found that mixed 5% Eu2O3 and ZnO NPs exhibit the highest photocatalytic activity (degradation efficiency of 96.5% after 180 min of UV irradiation) as compared with pure ZnO NPs (degradation efficiency of 80.3% after 180 min of UV irradiation). The increased photocatalytic activity of the optimum mixed Eu2O3 and ZnO NPs is due to the high crystallinity, high surface area with small particle size, and narrow energy gap.

Visible-light-driven Bi 2 O 3 /WO 3 composites with enhanced photocatalytic activity

DOE PAGES

Adhikari, Shiba P.; Dean, Hunter; Hood, Zachary D.; ...

2015-10-19

Semiconductor heterojunctions (composites) have been shown to be effective photocatalytic materials to overcome the drawbacks of low photocatalytic efficiency that results from electron–hole recombination and narrow photo-response range. We prepared a novel visible-light-driven Bi 2O 3/WO 3 composite photocatalyst by hydrothermal synthesis. The composite was characterized by scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area, Raman spectroscopy, photoluminescence spectroscopy (PL) and electrochemical impedance spectroscopy (EIS) to better understand the structures, compositions, morphologies and optical properties. Bi 2O 3/WO 3 heterojunction was found to exhibit significantly higher photocatalyticmore » activity towards the decomposition of Rhodamine B (RhB) and 4-nitroaniline (4-NA) under visible light irradiation compared to that of Bi 2O 3 and WO 3. A tentative mechanism for the enhanced photocatalytic activity of the heterostructured composite is discussed based on observed activity, band position calculations, photoluminescence, and electrochemical impedance data. Our study provides a new strategy for the design of composite materials with enhanced visible light photocatalytic performance.« less

Synthesis and study of photovoltaic performance on various photoelectrode materials for DSSCs: Optimization of compact layer on nanometer thickness

NASA Astrophysics Data System (ADS)

Surya, Subramanian; Thangamuthu, Rangasamy; Senthil Kumar, Sakkarapalayam Murugesan; Murugadoss, Govindhasamy

2017-02-01

Dye-sensitized solar cells (DSSCs) have gained widespread attention in recent years because of their low production costs, ease of fabrication process and tuneable optical properties, such as colour and transparency. In this work, we explored a strategy wherein nanoparticles of pure TiO2, TiO2sbnd SnO2 nanocomposite, Sn (10%) doped TiO2 and SnO2 synthesized by the simple chemical precipitation method were employed as photoelectrodes to enhance the photovoltaic conversion efficiency of solar cells. The nanoparticles were characterized by different characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM with EDX), transmission electron microscopy (TEM), high resolution electron microscopy (HR-TEM), UV-Visible absorbance (UV-vis), photoluminescence (PL), thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) measurements. Moreover, we also demonstrated the effect of thin compact layer in DSSCs by architecture with various precursor materials of different concentrations. We found that the optimized compact layer material TDIP (titanium diisopropoxide) with a concentration of 0.3 M % is produced the highest efficiency of 2.25% for Sn (10%) doped TiO2 electron transport material (ETM) and 4.38% was achieved for pure TiO2 ETM using SnCl2 compact layer with 0.1 M concentrations.

Gradient doping - a case study with Ti-Fe2O3 towards an improved photoelectrochemical response.

PubMed

Srivastav, Anupam; Verma, Anuradha; Banerjee, Anamika; Khan, Saif A; Gupta, Mukul; Satsangi, Vibha Rani; Shrivastav, Rohit; Dass, Sahab

2016-12-07

The present study investigates the effect of gradient doping on modifying the photoelectrochemical response of Ti-doped Fe 2 O 3 photoanodes for their use in sunlight based water splitting for hydrogen evolution. The deposition of a thin film over the ITO (tin doped indium oxide) substrate was carried out using a spray pyrolysis method. The concentration of dopant was varied from 0.5-8.0 at% and two sets of samples were also prepared with low to high (0.5-8%) and high to low (8-0.5%) dopant concentrations in the direction towards the substrate. The prepared thin films were characterized using X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) Spectroscopy, Secondary Ion Mass Spectroscopy (SIMS), X-ray Photoelectron Spectroscopy (XPS) and UV-visible Spectroscopy. The photoelectrochemical studies revealed that the deposition of dopant layers with a low to high concentration towards the substrate exhibited a highly improved photoresponse (200 times) in comparison to the pristine sample and a two fold enhancement in comparison to 2% Ti-doped Fe 2 O 3 . The improvement in the photoresponse has been attributed to the values of a high flat band potential, low resistance, high open circuit voltage, carrier separation efficiency, applied bias photon-to-current conversion efficiency (ABPE), and incident photon-to-current conversion efficiency (IPCE). A reduced charge transfer resistance has been demonstrated with Nyquist plots.

Methylglyoxal induced glycation and aggregation of human serum albumin: Biochemical and biophysical approach.

PubMed

Ahmed, Azaj; Shamsi, Anas; Khan, Mohd Shahnawaz; Husain, Fohad Mabood; Bano, Bilqees

2018-07-01

Serum protein glycation and formation of advanced glycation end products (AGEs) correlates with many diseases viz. diabetes signifying the importance of studying the glycation pattern of serum proteins. In our present study, methylglyoxal was investigated for its effect on the structure of human serum albumin (HSA); exploring the formation of AGEs and aggregates of HSA. The analytical tools employed includes intrinsic and extrinsic fluorescence, UV spectroscopy, far UV circular dichroism, Thioflavin T fluorescence, congo red binding, polyacrylamide gel electrophoresis (PAGE). UV and fluorescence spectroscopy revealed the structural transition of native HSA evident by new peaks and increased absorbance in UV spectra and quenched fluorescence in the presence of MG. Far UV CD spectroscopy revealed MG induced secondary structural alteration evident by reduced α-helical content. AGEs formation was confirmed by AGEs specific fluorescence. Increased ThT fluorescence and CR absorbance of 10mM MG incubated HSA suggests that glycated HSA results in the formation of aggregates of HSA. SEM and TEM were reported to have an insight of these aggregates. Molecular docking was also utilized to see site specific interaction of MG-HSA. This study is clinically significant as HSA is a clinically relevant protein which plays a crucial role in many diseases. Copyright © 2018 Elsevier B.V. All rights reserved.

Surface studies of low molecular weight photolysis products from UV-ozone oxidised polystyrene

NASA Astrophysics Data System (ADS)

Davidson, M. R.; Mitchell, S. A.; Bradley, R. H.

2005-05-01

The production of low molecular weight oxidised material during UV-ozone treatment of polystyrene has been studied by XPS, GC-MS, FTIR and UV/visible spectroscopy. XPS analysis of the oxidised polystyrene surfaces before and after washing with water or methanol indicates that the removal of oxidation products and the surface that remains after washing is strongly dependent on the choice of solvent. Methanol washing removes a greater proportion of the more highly oxidised carbonyl and carboxyl groups resulting in a surface with a lower oxygen content than that remaining after water washing. Extended exposure to UV-ozone treatment reveals a two-stage oxidation process with mono-substituted benzene rings such as benzaldehyde, acetophenone and benzoic acid being produced at exposure times less than 15 min. Compounds, more typical of those formed via dehydration reactions of existing oxidised species, are produced at longer exposure times. UV-visible spectroscopy and Fourier transform infrared spectroscopy also confirm the presence of carboxylic acid, aromatic ketones and esters. Measurements of water contact angle on a 10 min treated surface reveals that methanol washing produces a more hydrophilic surface than water washing, the resulting water contact angles being 47° and 62° respectively. Ageing of methanol washed surfaces for 24 h leads to a recovery of the water contact angle back to 62° which suggests some form of post-washing surface relaxation process. Since XPS analyses show no increase in the oxygen concentration of the methanol washed surfaces after a 24 h ageing period, the increase in contact angle found with ageing is attributed to the reorientation of very near-surface functional groups i.e. within the XPS sampling depth.

MgO NPs synthesis, capping and enhanced free radical effect on the bacteria and its cell morphology

NASA Astrophysics Data System (ADS)

Kushwaha, Amisha; Bagchi, T.

2018-05-01

Magnesium Oxide Nanoparticles (MgO NPs) commonly known as Magnesia is a white powder, hygroscopic material. MgO NPs were synthesized through four methods Co-precipitation method (Co-PM), Solution combustion (S-CoM) and Sol-gel method with starch (So-GSM) and CTAB (So-GCM), classified as template dependent and template independent method using magnesium nitrate hexahydrate (Mg(NO3).6H2O) as the precursor and comparative analysis was done through DLS. The order of hydrodynamic diameters of four different synthesis method of MgO NPs is Co-PM LA-MgO NPs> MgO NPs responding.

Group 12 dithiocarbamate complexes: synthesis, spectral studies and their use as precursors for metal sulfides nanoparticles and nanocomposites.

PubMed

Ajibade, Peter A; Ejelonu, Benjamin C

2013-09-01

Zn(II), Cd(II) and Hg(II) dithiocarbamate complexes have been synthesized and characterized by elemental analysis, thermogravimetric analysis, UV-Vis, FTIR, (1)H- and (13)C NMR spectroscopy. The complexes were thermolysed at 180 °C and used as single molecule precursors for the synthesis of HDA capped ZnS, CdS and HgS nanoparticles and polymethylmethacrylate (PMMA) nanocomposites. The optical and structural properties of the nanoparticles and nanocomposites were studied by UV-Vis, PL, XRD and SEM. The crystallites sizes of the nanoparticles varied between 3.03 and 23.45 nm. SEM and EDX analyses of the nanocomposites confirmed the presence of the nanoparticles in the polymer matrix. Copyright © 2013 Elsevier B.V. All rights reserved.

A comparison of antioxidative capacities of fruit juices, drinks and nectars, as determined by EPR and UV-vis spectroscopies

NASA Astrophysics Data System (ADS)

Bartoszek, Mariola; Polak, Justyna

2016-01-01

The differences in the Trolox Equivalent Antioxidant Capacity (TEAC) values at the same incubation time obtained by two different techniques: electron paramagnetic resonance (EPR) spectroscopy and ultraviolet visible (UV-vis) spectroscopy, which use the same antioxidant-free radical reaction mechanism, were determined for fruit juices, nectars and drinks. For this study, the stable free radical 1,1-Diphenyl-2-picryl-hydrazyl (DPPH•) was used. The antioxidant capacity was presented in Trolox Equivalents, e.g., μM trolox per 100 ml of sample. All of the studied fruit juices, drinks and nectars showed antioxidative properties. Dependencies between TEAC values and the percent fruit content and sample color were observed for the studied beverages. It was found that EPR spectroscopy is the more adequate method for determining TEAC values for these kinds of samples.

Efficient water disinfection with Ag2WO4-doped mesoporous g-C3N4 under visible light.

PubMed

Li, Yi; Li, Yanan; Ma, Shuanglong; Wang, Pengfei; Hou, Qianlei; Han, Jingjing; Zhan, Sihui

2017-09-15

Ag 2 WO 4 /g-C 3 N 4 composite photocatalyst was synthesized by polymerization of thiourea and ammonia chloride combined with the deposition-precipitation method, which was applied as an efficient visible-light driven photocatalyst for inactivating Escherichia coli (E. coli). The physicochemical properties of these photocatalysts were systematically characterized by various techniques such as SEM, TEM, XRD, FT-IR, BET, UV-vis DRS and PL. The synthesized photocatalysts exhibited outstandingly enhanced photocatalytic disinfection efficiency compared with that of pure g-C 3 N 4 and Ag 2 WO 4 under visible light. Furthermore, the optimal mass ratio of the Ag 2 WO 4 to g-C 3 N 4 was 5wt%, and a number of live bacteria could be completely inactivated with Ag 2 WO 4 (5%)/g-C 3 N 4 (100μg/mL) after 90min under visible light irradiation. The high disinfection efficiency is due to the synergetic effect between g-C 3 N 4 and Ag 2 WO 4 , including a good distribution of Ag 2 WO 4 particles on the surface of g-C 3 N 4 and an improved separation rate of photogenerated electron-hole pairs. The enhanced disinfection mechanism was also investigated using photogenerated current densities and electrochemical impedance spectroscopy (EIS). Considering the bulk availability and excellent disinfection activity of Ag 2 WO 4 /g-C 3 N 4 composite, it is a promising solar-driven photocatalyst for cleaning the microbial contaminated water. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of citric acid on material properties of ZnGa2O4:Cr3+ nanopowder prepared by sol-gel method

NASA Astrophysics Data System (ADS)

Hussen, Megersa K.; Dejene, Francis B.; Gonfa, Girma G.

2018-05-01

This paper reports the material properties of Cr3+ (1.0 mol%)-doped ZnGa2O4 nanopowders prepared by citric acid-assisted sol-gel method with metal cations (Zn + Ga) to citric (M:CA) molar ratios of (1:0.5, 1:1, 1:3 and 1:4). The X-ray diffraction (XRD) results show that the synthesized nanoparticles are cubic structured and concentration of citric acid did not affect the structure. The scanning electron microscope (SEM) shows that the increase of the M:CA molar ratio favors the formation of smaller nano particle of ZnGa2O4:Cr3+. The photoluminescence (PL) is found to be maximum for sample with M:CA ratio of 1:1. Further increase in citric acid leads to significant decrease in the PL intensity. Energy-dispersive X-ray spectroscopy (EDS) measurement confirms the presence of the Zn, Ga, O and Cr ions. Ultraviolet-visible (UV-Vis) spectrophotometer measurement shows an increase in reflectance in visible region and the energy band gap was found to decrease with an increase in citric acid molar ratio. The emission spectra, particle size and photoluminescence lifetimes are comparable with reports on bioimaging applications.

TiO2/PbS/ZnS heterostructure for panchromatic quantum dot sensitized solar cells synthesized by wet chemical route

NASA Astrophysics Data System (ADS)

Bhat, T. S.; Mali, S. S.; Sheikh, A. D.; Korade, S. D.; Pawar, K. K.; Hong, C. K.; Kim, J. H.; Patil, P. S.

2017-11-01

So far we developed the efficient photoelectrodes which can harness the UV as well as the visible regime of the solar spectrum effectively. In order to exploit a maximum portion of solar spectrum, it is necessary to study the synergistic effect of a photoelectrode comprising UV and visible radiations absorbing materials. Present research work highlights the efforts to study the synchronized effect of TiO2 and PbS on the power conversion efficiency of quantum dot sensitized solar cell (QDSSC). A cascade structure of TiO2/PbS/ZnS QDSSC is achieved to enhance the photoconversion efficiency of TiO2/PbS system by incorporating a surface passivation layer of ZnS which avoids the recombination of charge carriers. A QDSSC is fabricated using a simple and cost-effective technique such as hydrothermally grown TiO2 nanorod arrays decorated with PbS and ZnS using successive ionic layer adsorption and reaction (SILAR) method. Synthesized electrode materials are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), High resolution-transmission electron microscopy (TEM), STEM-EDS mapping, optical and solar cell performances. Phase formation of TiO2, PbS and ZnS get confirmed from the XPS study. FE-SEM images of the photoelectrode show uniform coverage of PbS QDs onto the TiO2 nanorods which increases with increasing number of SILAR cycles. The ZnS layer not only improves the charge transport but also reduces the photocorrosion of lead chalcogenides in the presence of a liquid electrolyte. Finally, the photoelectrochemical (PEC) study is carried out using an optimized photoanode comprising TiO2/PbS/ZnS assembly. Under AM 1.5G illumination the TiO2/PbS/ZnS QDSSC photoelectrode shows 4.08 mA/cm2 short circuit current density in a polysulfide electrolyte which is higher than that of a bare TiO2 nanorod array.

Synthesis, characterizations and anti-bacterial activities of pure and Ag doped CdO nanoparticles by chemical precipitation method

NASA Astrophysics Data System (ADS)

Sivakumar, S.; Venkatesan, A.; Soundhirarajan, P.; Khatiwada, Chandra Prasad

2015-02-01

In the present study, synthesized pure and Ag (1%, 2%, and 3%) doped Cadmium Oxide (CdO) nanoparticles by chemical precipitation method. Then, the synthesized products were characterized by thermo gravimetric-differential thermal analysis (TG-DTA), X-ray diffraction (XRD) analysis, Fourier transform infrared (FT-IR) spectroscopy, Ultra violet-Vis diffused reflectance spectroscopy (UV-Vis-DRS), Scanning electron microscopy (SEM), Energy dispersive X-rays (EDX) spectroscopy, and anti-bacterial activities, respectively. The transition temperatures and phase transitions of Cd(OH)2 to CdO at 400 °C was confirmed by TG-DTA analysis. The XRD patterns show the cubic shape and average particle sizes are 21, 40, 34, and 37 nm, respectively for pure and Ag doped samples. FT-IR study confirmed the presence of CdO and Ag at 677 and 459 cm-1, respectively. UV-Vis-DRS study shows the variation on direct and indirect band gaps. The surface morphologies and elemental analysis have been confirmed from SEM and with EDX. In addition, the synthesized products have been characterized by antibacterial activities against Gram-positive and negative bacteria. Further, the present investigation suggests that CdO nanoparticles have the great potential applications on various industrial and medical fields of research.

Green synthesis of selenium nanoparticles conjugated Clausena dentata plant leaf extract and their insecticidal potential against mosquito vectors.

PubMed

Sowndarya, P; Ramkumar, G; Shivakumar, M S

2017-12-01

Mosquitoes are major vectors for the transmission of many diseases like chikungunya, malaria, dengue, zika, etc. worldwide. In the present study, selenium nanoparticles (SeNPs) were synthesized from Clausena dentata and were tested for their larvicidal efficacy against the fourth-instar larvae of Anopheles stephensi, Aedes Aegypti, and Culex quinquefasciatus. The synthesized nanoparticles were characterized using UV-Vis spectroscopy, Fourier Transform Infrared Radiation (FTIR) spectroscopy, EDaX, and SEM. The results recorded from UV-Vis spectroscopy show the peak absorption spectrum at 420 nm. In FTIR, the maximum peak value is 2922.25 cm -1 assigned to N-H group (amide group). In EDaX analysis shows peak around 72.64 which confirm the binding intensity of selenium. In SEM analysis, the synthesized SeNPs sizes were ranging from 46.32 nm to 78.88 nm. The synthesized SeNPs produced high mortality with very low concentration (LC 50 ) were 240.714 mg/L; 104.13 mg/L, and 99.602 mg/L for A. stephensi, A. Aegypti, and C. quinquefasciatus, respectively. These results suggest that the C. dentata leaf extract-mediated biosynthesis of SeNPs has the potential to be used as an ideal ecofriendly approach toward the control of mosquito vectors at early stages.

Green engineered ZnO nanopowders by Banyan Tree and E. tirucalli plant latex: auto ignition route, photoluminescent and photocatalytic properties

NASA Astrophysics Data System (ADS)

Anilkumar, M. R.; Nagaswarupa, H. P.; Anantharaju, K. S.; Gurushantha, K.; Pratapkumar, C.; Prashantha, S. C.; Shashi Shekhar, T. R.; Nagabhushana, H.; Sharma, S. C.; Vidya, Y. S.; Prasad, Daruka

2015-03-01

A simple and eco-friendly solution combustion route was used to prepare ZnO nanoparticles (ZNPs) using Banyan Tree (BT) and Euphorbia tirucalli (ET) plant latexes as fuels. The final products were characterized by powder x-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), UV-visible, scanning electron microcopy (SEM) and transmission electron microscopy (TEM). The PXRD result reveals the formation of hexagonal phase with Wurtzite structure. The crystallite size obtained from TEM was found to be ˜20-25 nm. SEM results reveal rose-like morphology with BT latex and hexagonal shaped with ET latex. The energy band gap of ZNPs obtained by BT and ET latex were found to be 3.20 and 3.38 eV, respectively. Photoluminescence (PL) emission peaks at ˜421, 458, 505, 522, 628 and 695 nm were observed in both the samples when excited at 383 nm. These emission peaks were mainly attributed to deep level oxygen (blue-green) defect and exciton (UV) defects, respectively. The international commission on illumination (CIE) chromaticity co-ordinates, as well as co-ordinated color temperature (CCT), were estimated from the emission spectra; the values (x, y) were very close to national television system committee (NTSC) standard values of pure white emission. Photocatalytic activity (PCA) of ZNPs prepared was studied in detail. The ZNPs prepared using BT latex showed highest PCA under sunlight. The results demonstrate that the synthesized product could be quite useful for display applications as well as photocatalyst. Further, the material prepared by this route was found to be non-toxic, environmentally friendly and could be a potential alternative to economical routes.

Improvement on controllable fabrication of streptavidin-modified three-layer core-shell Fe3O4@SiO2@Au magnetic nanocomposites with low fluorescence background.

PubMed

Jiang, Hongrong; Zeng, Xin; Xi, Zhijiang; Liu, Ming; Li, Chuanyan; Li, Zhiyang; Jin, Lian; Wang, Zhifei; Deng, Yan; He, Nongyue

2013-04-01

In present study, we put forward an approach to prepare three-layer core-shell Fe3O4@SiO2@Au magnetic nanocomposites via the combination of self-assembling, seed-mediated growing and multi-step chemical reduction. The Fe3O4@SiO2@Au magnetic nanocomposites were analyzed and characterized by transmission electron microscope (TEM), scanning electronic microscope (SEM), energy dispersive spectrometer analysis (EDS), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), and ultraviolet and visible spectrophotometer (UV-Vis). TEM and SEM characterizations showed that the FeO4@SiO2@Au nanocomposites were obtained successfully with three-layer structures, especially a layer of thin, smooth and continuous gold shell. The average diameter of Fe3O4@SiO2@Au nanocomposites was about 600 nm and an excellent dispersity was observed for the as-prepared nanoparticles. EDS characterizations demonstrated that the nanocomposites contained three elements of the precursors, Fe, Si, and Au. Furthermore, FT-IR showed that the silica and gold shell were coated successfully. UV-Vis and VSM characterizations showed that the Fe3O4@SiO2@Au nanocomposites exhibited good optical and magnetic property, and the saturation magnetization was 25.76 emu/g. In conclusion, the Fe3O4@SiO2@Au magnetic nanocomposites with three-layer core-shell structures were prepared. Furthermore, Fe3O4@SiO2@Au magnetic nanocomposites were modified with streptavidin (SA) successfully, and it was validated that they performed low fluorescence background, suggesting that they should have good applications especially in bioassay based on fluorescence detection through bonding the biotinylated fluorescent probes.

A facile biomimetic preparation of highly stabilized silver nanoparticles derived from seed extract of Vigna radiata and evaluation of their antibacterial activity

NASA Astrophysics Data System (ADS)

Choudhary, Manoj Kumar; Kataria, Jyoti; Cameotra, Swaranjit Singh; Singh, Jagdish

2016-01-01

The significant antibacterial activity of silver nanoparticles draws the major attention toward the present nanobiotechnology. Also, the use of plant material for the synthesis of metal nanoparticles is considered as a green technology. In this context, a non-toxic, eco-friendly, and cost-effective method has been developed for the synthesis of silver nanoparticles using seed extract of mung beans ( Vigna radiata). The synthesized nanoparticles have been characterized by UV-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), atomic absorption spectroscopy (AAS), and X-ray diffraction (XRD). The UV-visible spectrum showed an absorption peak at around 440 nm. The different types of phytochemicals present in the seed extract synergistically reduce the Ag metal ions, as each phytochemical is unique in terms of its structure and antioxidant function. The colloidal silver nanoparticles were observed to be highly stable, even after 5 months. XRD analysis showed that the silver nanoparticles are crystalline in nature with face-centered cubic geometry and the TEM micrographs showed spherical particles with an average size of 18 nm. Further, the antibacterial activity of silver nanoparticles was evaluated by well-diffusion method and it was observed that the biogenic silver nanoparticles have an effective antibacterial activity against Escherichia coli and Staphylococcus aureus. The outcome of this study could be useful for nanotechnology-based biomedical applications.

Effect of the solvent on the size of clay nanoparticles in solution as determined using an ultraviolet-visible (UV-Vis) spectroscopy methodology.

PubMed

Alin, Jonas; Rubino, Maria; Auras, Rafael

2015-06-01

Ultraviolet-visible (UV-Vis) spectroscopy methodology was developed and utilized for the in situ nanoscale measurement of the size of mineral clay agglomerates in various liquid suspensions. The clays studied were organomodified and unmodified montmorillonite clays (I.44p, Cloisite 93a, and PGN). The methodology was compared and validated against dynamic light scattering (DLS) analysis. The method was able to measure clay agglomerates in solvents in situations where DLS analysis was unsuccessful due to the shapes, polydispersity, and high aspect ratios of the clay particles and the complexity of the aggregates, or dispersion medium. The measured clay agglomerates in suspension were found to be in the nanometer range in the more compatible solvents, and their sizes correlated with the Hansen solubility parameter space distance between the clay modifiers and the solvents. Mass detection limits for size determination were in the range from 1 to 9 mg/L. The methodology thus provides simple, rapid, and inexpensive characterization of clays or particles in the nano- or microsize range in low concentrations in various liquid media, including complex mixtures or highly viscous fluids that are difficult to analyze with DLS. In addition, by combining UV-VIS spectroscopy with DLS it was possible to discern flocculation behavior in liquids, which otherwise could result in false size measurements by DLS alone.

Fingerprinting profile of polysaccharides from Lycium barbarum using multiplex approaches and chemometrics

USDA-ARS?s Scientific Manuscript database

Techniques including ultraviolet-visible spectra (UV), high performance size-exclusion chromatography (HPSEC), fourier-transform infrared spectroscopy (FT-IR) and pre-column derivatization high-performance liquid chromatography (PCD-HPLC) were used in the fingerprinting analysis of Lycium barbarum p...

Potential development of a new cotton-based antimicrobial wipe

USDA-ARS?s Scientific Manuscript database

The adsorption of alkyl-dimethyl-benzyl-ammonium chloride (ADBAC), a cationic surfactant commonly employed as an antimicrobial agent, on greige and bleached nonwoven cotton fabrics was investigated using UV/visible spectroscopy. Initial results have shown that greige cotton adsorbs roughly three tim...

Characterization of pure and composite resorcinol formaldehyde aerogels doped with silver

NASA Astrophysics Data System (ADS)

Attia, S. M.; Abdelfatah, M. S.; Mossad, M. M.

2017-07-01

A series of Resorcinol Formaldehyde (RF) aerogels composites with nanoparticles of sliver were prepared by the sol-gel method at different concentrations doped silver. FTIR spectra of pure and composite RF aerogels show six absorption bands attributed to -OH groups bonded to the benzene ring, stretching of -CH2- bonds and aromatic ring stretching. FTIR results ensured that sliver particles do not interact with aerogel network. UV-visible spectrum of pure silver show an absorbance peak at 420 nm attributed to the surface plasmon excitation of sliver Nano spheres. UV-visible spectral of pure and composite RF aerogels shows a steep decrease of absorption with wavelength after 500 nm, making sample’s color reddish brown. TEM and SEM images of pure and composite RF aerogels revealed that the textural arrangement of RF aerogels can be described as densely packed small nodules.

Highly textured and transparent RF sputtered Eu2O3 doped ZnO films

PubMed Central

Sreedharan, Remadevi Sreeja; Ganesan, Vedachalaiyer; Sudarsanakumar, Chellappan Pillai; Bhavsar, Kaushalkumar; Prabhu, Radhakrishna; Mahadevan Pillai, Vellara Pappukutty Pillai

2015-01-01

Background Zinc oxide (ZnO) is a wide, direct band gap II-VI oxide semiconductor. ZnO has large exciton binding energy at room temperature, and it is a good host material for obtaining visible and infrared emission of various rare-earth ions. Methods Europium oxide (Eu2O3) doped ZnO films are prepared on quartz substrate using radio frequency (RF) magnetron sputtering with doping concentrations 0, 0.5, 1, 3 and 5 wt%. The films are annealed in air at a temperature of 773 K for 2 hours. The annealed films are characterized using X-ray diffraction (XRD), micro-Raman spectroscopy, atomic force microscopy, ultraviolet (UV)-visible spectroscopy and photoluminescence (PL) spectroscopy. Results XRD patterns show that the films are highly c-axis oriented exhibiting hexagonalwurtzite structure of ZnO. Particle size calculations using Debye-Scherrer formula show that average crystalline size is in the range 15–22 nm showing the nanostructured nature of the films. The observation of low- and high-frequency E2 modes in the Raman spectra supports the hexagonal wurtzite structure of ZnO in the films. The surface morphology of the Eu2O3 doped films presents dense distribution of grains. The films show good transparency in the visible region. The band gaps of the films are evaluated using Tauc plot model. Optical constants such as refractive index, dielectric constant, loss factor, and so on are calculated using the transmittance data. The PL spectra show both UV and visible emissions. Conclusion Highly textured, transparent, luminescent Eu2O3 doped ZnO films have been synthesized using RF magnetron sputtering. The good optical and structural properties and intense luminescence in the ultraviolet and visible regions from the films suggest their suitability for optoelectronic applications. PMID:25765728

Biomolecule-controlled hydrothermal synthesis of C-N-S-tridoped TiO2 nanocrystalline photocatalysts for NO removal under simulated solar light irradiation.

PubMed

Wang, Yawen; Huang, Yu; Ho, Wingkei; Zhang, Lizhi; Zou, Zhigang; Lee, Shuncheng

2009-09-30

In this study, C-N-S-tridoped titanium dioxide (TiO(2)) nanocrystals were synthesized by using a facile hydrothermal method in the presence of a biomolecule l-cysteine. This biomolecule could not only serve as the common source for the carbon, sulfur and nitrogen tridoping, but also could control the final crystal phases and morphology. The resulting materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption and UV-vis diffuse reflectance spectroscopy. XPS analysis revealed that S was incorporated into the lattice of TiO(2) through substituting oxygen atoms, N might coexist in the forms of N-Ti-O and Ti-O-N in tridoped TiO(2) and most C could form a mixed layer of carbonate species deposited on the surface of TiO(2) nanoparticles. The photocatalytic activities of the samples were tested on the removal of NO at typical indoor air level in a flow system under simulated solar light irradiation. The tridoped TiO(2) samples showed much higher removal efficiency than commercial P25 and the undoped counterpart photocatalyst. The enhanced visible light photocatalytic activity of C-N-S-tridoped TiO(2) nanocrystals was explained on the basis of characterizations. The possible formation process of the monodispersed C-N-S-tridoped anatase TiO(2) nanocrystals was also proposed. This study provides a new method to prepare visible light active TiO(2) photocatalyst.

Photophysical and Photocatalytic Properties of BiSnSbO6 under Visible Light Irradiation

PubMed Central

Huang, Panqi

2018-01-01

BiSnSbO6 with strong photocatalytic activity was first fabricated by a high-temperature, solid-state sintering method. The resulting BiSnSbO6 was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The results showed that BiSnSbO6, with a pyrochlore structure and a cubic crystal system by a space group Fd3m, was well crystallized. The lattice parameter or the band gap of BiSnSbO6 was 10.234594 Å or 2.83 eV. Compared with N-doped TiO2, BiSnSbO6 showed higher photocatalytic activity in the degradation of benzotriazole and rhodamine B. The apparent first-order rate constant for BiSnSbO6 in the degradation of benzotriazole and rhodamine B was 0.0182 min−1 and 0.0147 min−1, respectively. On the basis of the scavenger experiment, during the photocatalytic process, the main active species were arranged in order of increasing photodegradation rate: •OH < •O2− < h+. The removal rate of benzotriazole or rhodamine B was approximately estimated to be 100% with BiSnSbO6 as a photocatalyst after 200 min visible-light irradiation. Plentiful CO2 produced by the experiment indicated that benzotriazole or rhodamine B was continuously mineralized during the photocatalytic process. Finally, the possible photodegradation pathways of benzotriazole and rhodamine B were deduced. PMID:29587420

Demonstration of miniaturized 20mW CW 280nm and 266nm solid-state UV laser sources

NASA Astrophysics Data System (ADS)

Landru, Nicolas; Georges, Thierry; Beaurepaire, Julien; Le Guen, Bruno; Le Bail, Guy

2015-02-01

Visible 561 nm and 532 nm laser emissions from 14-mm long DPSS monolithic cavities are frequency converted to deep UV 280 nm and 266 nm in 16-mm long monolithic external cavities. Wavelength conversion is fully insensitive to mechanical vibrations and the whole UV laser sources fit in a miniaturized housing. More than 20 mW deep UV laser emission is demonstrated with high power stability, low noise and good beam quality. Aging tests are in progress but long lifetimes are expected thanks to the cavity design. Protein detection and deep UV resonant Raman spectroscopy are applications that could benefit from these laser sources.

The effect of simulated low earth orbit radiation on polyimides (UV degradation study)

NASA Technical Reports Server (NTRS)

Forsythe, John S.; George, Graeme A.; Hill, David J. T.; Odonnell, James H.; Pomery, Peter J.; Rasoul, Firas A.

1995-01-01

UV degradation of polyimide films in air and vacuum were studied using UV-visible, ESR, FTIR, and XPS spectroscopies. The UV-visible spectra of polyimide films showed a blue shift in the absorption compared to Kapton. This behavior was attributed to the presence of bulky groups and kinks along the polymer chains which disrupt the formation of a charge transfer complex. The UV-visible spectra showed also that UV irradiation of polyimides result extensively in surface degradation, leaving the bulk of the polymer intact. ESR spectra of polyimides irradiated in vacuum revealed the formation of stable carbon-centered radicals which give a singlet ESR spectrum, while polyimides irradiated in air produced an asymmetric signal shifted to a lower magnetic field, with a higher g value and line width. This signal was attributed to oxygen-cenetered radicals of peroxy and/or alkoxy type. The rate of radical formation in air was two fold higher than for vacuum irradiation, and reached a plateau after a short time. This suggests a continuous depletion of radicals on the surface via an ablative degradation process. FTIR, XPS, and weight loss studies supported this postulate. An XPS study of the surface indicated a substantial increase in the surface oxidation after irradiation in air. The sharp increase in the C-O binding energy peak relative to the C-C peak was believed to be associated with an aromatic ring opening reaction.

Characterization of graphene oxide produced by Hummers method and its supercapacitor applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akgül, Ö., E-mail: omeraakgul@gmail.com; Tanrıverdi, A., E-mail: aa.kudret@hotmail.com; Alver, Ü., E-mail: ualver@ktu.edu.tr

2016-03-25

In this study, Graphene Oxide (GO) is produced using Hummers method. The produced GO were investigated by x-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), UV-Vis spectrum, Raman spectroscopy and scanning electron microscopy (SEM). GO films on Ni foam were prepared by doctor-blading technique. The electrochemical performances of the as-synthesized GO electrode was evaluated using cyclic voltammetry (CV) in 6 M KOH aqueous solution. Capacitances of GO electrode was measured as 0.76 F/g.

Studies on visible light photocatalytic and antibacterial activities of nanostructured cobalt doped ZnO thin films prepared by sol-gel spin coating method.

PubMed

Poongodi, G; Anandan, P; Kumar, R Mohan; Jayavel, R

2015-09-05

Nanostructured cobalt doped ZnO thin films were deposited on glass substrate by sol-gel spin coating technique and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and UV-Vis spectroscopy. The XRD results showed that the thin films were well crystalline with hexagonal wurtzite structure. The results of EDAX and XPS revealed that Co was doped into ZnO structure. FESEM images revealed that the films possess granular morphology without any crack and confirm that Co doping decreases the grain size. UV-Vis transmission spectra show that the substitution of Co in ZnO leads to band gap narrowing. The Co doped ZnO films were found to exhibit improved photocatalytic activity for the degradation of methylene blue dye under visible light in comparison with the undoped ZnO film. The decrease in grain size and extending light absorption towards the visible region by Co doping in ZnO film contribute equally to the improved photocatalytic activity. The bactericidal efficiency of Co doped ZnO films were investigated against a Gram negative (Escherichia coli) and a Gram positive (Staphylococcus aureus) bacteria. The optical density (OD) measurement showed better bactericidal activity at higher level of Co doping in ZnO. Copyright © 2015 Elsevier B.V. All rights reserved.

A facile synthesis of Zn(x)Cd(1-x)S/CNTs nanocomposite photocatalyst for H2 production.

PubMed

Wang, Lei; Yao, Zhongping; Jia, Fangzhou; Chen, Bin; Jiang, Zhaohua

2013-07-21

The sulfide solid solution has become a promising and important visible-light-responsive photocatalyst for hydrogen production nowadays. Zn(x)Cd(1-x)S/CNT nanocomposites were synthesized to improve the dispersion, adjust the energy band gap, and enhance the separation of the photogenerated electrons and holes. The as-prepared photocatalysts were characterized by scanning electron-microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance spectra (UV-visible), respectively. And the effects of CNTs on structure, composition and optical absorption property of the sulfide solid solutions were investigated along with their inherent relationships. For Zn0.83Cd0.17S/CNTs, sulfide solid solution is assembled along the CNTs orderly, with a diameter of 100 nm or so. XPS analysis shows that there is bonding effect between the solid solutions and the CNTs due to the strong adsorption of Zn(2+) and Cd(2+) on the surface of CNTs. There are two obvious absorption edges for Zn0.83Cd0.17S/CNTs, corresponding to two kinds of sulfide solid solutions with different molar ratios of Zn/Cd. The hybridization of solid solutions with CNTs makes the absorption spectrum red shift. The photocatalytic property was evaluated by splitting Na2S + Na2SO3 solution into H2, and the highest rate of H2 evolution of 6.03 mmol h(-1) g(-1) was achieved over Zn0.83Cd0.17S/CNTs. The high activity of photocatalytic H2 production is attributed to the following factors: (1) the optimum band gap and a moderate position of the conduction band (which needs to match the irradiation spectrum of the Xe lamp best), (2) the efficient separation of photogenerated electrons and holes by hybridization, and (3) the improvement of the dispersion of nanocomposites by assembling along the CNTs as well.

Electronic structure and bonding interactions in Ba1- x Sr x Zr0.1Ti0.9O3 ceramics

NASA Astrophysics Data System (ADS)

Mangaiyarkkarasi, Jegannathan; Sasikumar, Subramanian; Saravanan, Olai Vasu; Saravanan, Ramachandran

2017-06-01

An investigation on the precise electronic structure and bonding interactions has been carried out on Ba1- x Sr x Zr0.1Ti0.9O3 (short for BSZT, x = 0, 0.05, 0.07 and 0.14) ceramic systems prepared via high-temperature solid state reaction technique. The influence of Sr doping on the BSZT structure has been examined by characterizing the prepared samples using PXRD, UV-visible spectrophotometry, SEM and EDS. Powder profile refinement of X-ray data confirms that all the synthesized samples have been crystallized in cubic perovskite structure with single phase. Charge density distribution of the BSZT systems has been completely analyzed by the maximum entropy method (MEM). Co-substitution of Sr at the Ba site and Zr at the Ti site into the BaTiO3 structure presents the ionic nature between Ba and O ions and the covalent nature between Ti and O ions, revealed from MEM calculations. Optical band gap values have been evaluated from UV-visible absorption spectra. Particles with irregular shapes and well defined grain boundaries are clearly visualized from SEM images. The phase purity of the prepared samples is further confirmed by EDS qualitative spectral analysis.

Enhanced photocatalytic activity of ZnO/CuO nanocomposite for the degradation of textile dye on visible light illumination.

PubMed

Saravanan, R; Karthikeyan, S; Gupta, V K; Sekaran, G; Narayanan, V; Stephen, A

2013-01-01

The photocatalytic degradation of organic dyes such as methylene blue and methyl orange in the presence of various percentages of composite catalyst under visible light irradiation was carried out. The catalyst ZnO nanorods and ZnO/CuO nanocomposites of different weight ratios were prepared by new thermal decomposition method, which is simple and cost effective. The prepared catalysts were characterized by different techniques such as X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and UV-visible absorption spectroscopy. Further, the most photocatalytically active composite material was used for degradation of real textile waste water under visible light illumination. The irradiated samples were analysed by total organic carbon and chemical oxygen demand. The efficiency of the catalyst and their photocatalytic mechanism has been discussed in detail. Copyright © 2012 Elsevier B.V. All rights reserved.

Investigation of the visible light photocatalytic activity of BiVO4 prepared by sol gel method assisted by ultrasonication.

PubMed

Deebasree, J P; Maheskumar, V; Vidhya, B

2018-07-01

Visible light induced photocatalyst BiVO 4 with monoclinic scheelite structure has been synthesised via sol gel method assisted by ultrasonication. The prepared samples were characterised using X-ray diffraction (XRD), scanning electron microscope (SEM), UV-Vis diffused reflectance spectroscopy (DRS) techniques. The photocatalytic efficiency was evaluated by decolourisation of MB under visible light irradiation. The effect of ultrasound output power on the properties of BiVO 4 during and after preparation by sol-gel method has been compared with normal agitated sample (As prepared). The power of ultrasonic vibration has been varied and an ideal output power which yields better catalytic efficiency is determined. BiVO 4 sonicated with 80 W during preparation 80 W (D) exhibited relatively high surface area, better surface morphology and better catalytic efficiency compared to other samples which were sonicated with 100, 160 and 200 W. The results signify that the photodegradation rate of BiVO 4 80 W (D) sample is high up to 96% in 90 min compared to other samples. Change in morphology leading to better catalytic efficiency was obtained just by exposing the sample to ultrasonic radiation without addition of any surfactant. The recovery test showed that the sample was stable for four consecutive cycles. Using radical test, a reasonable mechanism for photodegradation has been proposed. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhanced photocatalytic activity of hydrogenated and vanadium doped TiO2 nanotube arrays grown by anodization of sputtered Ti layers

NASA Astrophysics Data System (ADS)

Motola, Martin; Satrapinskyy, Leonid; Čaplovicová, Mária; Roch, Tomáš; Gregor, Maroš; Grančič, Branislav; Greguš, Ján; Čaplovič, Ľubomír; Plesch, Gustav

2018-03-01

TiO2 nanotube (TiNT) arrays were grown on silicon substrate via electrochemical anodization of titanium films sputtered by magnetron. To improve the photocatalytic activity of arrays annealed in air (o-TiNT), doping of o-TiNT with vanadium was performed (o-V/TiNT). These non-doped and doped TiNT arrays were also hydrogenated in H2/Ar atmosphere to r-TiNT and r-V/TiNT samples, respectively. Investigation of composition and morphology by X-ray diffraction (XRD), electron microscopy (SEM and TEM) and X-ray photoelectron spectroscopy (XPS) showed the presence of well-ordered arrays of anatase nanotubes with average diameter and length of 100 nm and 1.3 μm, respectively. In both oxidized and reduced V-doped samples, vanadium is partly dissolved in the structure of anatase and partly deposited in form of oxide on the nanotube surface. Vanadium-doped and reduced samples exhibited higher rates in the photodegradation of organic dyes (compared to non-modified o-TiNT sample) and this is caused by limitation of electron-hole recombination rates and by shift of the energy gap into visible region. The photocatalytic activity was measured under UV, sunlight and visible irradiation, and the corresponding efficiency increased in the order (o-TiNT) < (r-TiNT) < (o-V/TiNT) < (r-V/TiNT). Under visible light, only r-TiNT and r-V/TiNT showed significant photocatalytic activity.

Mesoporous Ga-TiO₂: Role of Oxygen Vacancies for the Photocatalytic Degradation Under Visible Light.

PubMed

Myilsamy, M; Mahalakshmi, M; Subha, N; Murugesan, V

2018-02-01

Gallium doped mesoporous TiO2 with different weight percentages were synthesized by sol-gel method using Pluronic P123 as the structure directing template. The physico-chemical properties of all the synthesized catalysts were determined by XRD, TEM, SEM-EDAX, N2 adsorption-desorption studies, XPS, UV-vis DRS, FT-IR and photoluminescence spectroscopy. 1.0 wt% Ga-TiO2 exhibited the highest photocatalytic efficiency among all the synthesized materials under visible light due to the high surface area, reduced band gap and suppressed electron-hole recombination. Ga3+ ions substitutions for Ti4+ ions in TiO2 lattice created oxygen vacancies in TiO2 lattice, which created a defect energy level below the conduction band of TiO2 and hence the band gap was reduced. The oxygen vacancy defects was playing significant role to improve the adsorption of oxygen molecules, hydroxide ions and cationic rhodamine B (RhB) on TiO2 surface in an aqueous medium. The lifetime of the charge carriers was also enhanced by trapping the photogenerated electrons in oxygen vacancies and transferring them to the adsorbed O2 to produce superoxide anion radicals (O-. 2 ). The photo-induced holes at valence band reduced the adsorbed OH- ions and produced a large number of .OH radicals, which subsequently degraded the RhB. Hence oxygen vacancies created by gallium doping on TiO2 enhanced the photocatalytic efficiency for the degradation of RhB under visible light.